Goniometer

ABSTRACT

A goniometer includes a base, a compound member supported by the base, a light-directing element operably mounted on the compound member, optically connected to a coherent light source, and disposed toward an optical filter, a first actuator disposed along a first axis and operably coupled to the base for translating the light-directing element along a first arcuate path disposed in a first plane; and a second actuator disposed along a second axis and operably coupled to the compound member for translating the light-directing element along a second arcuate path disposed in a second plane, wherein the first plane is orthogonal to the second plane, and wherein the first and second axes are co-planar, for directing coherent light at an angle that is normal to the optical filter.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based from U.S. Provisional Application Ser. No.60/276,999 filed on Mar. 19, 2001 and entitled “AUTOMATED APPARATUS FORTESTING OPTICAL FILTERS”. This application is related to an applicationentitled AUTOMATED APPARATUS FOR TESTING OPTICAL FILTERS, having U.SPat. App. Ser. No. 10/102,200, filed Mar. 19, 2002, an applicationentitled METHOD AND APPARATUS FOR CALIBRATING A VISION SYSTEM TO A PARTSHANDLING DEVICE, having U.S. Pat. App. Ser. No. 10/102,515, filed onMar. 19, 2002, and an application entitled FLEXURE, having U.S. Pat.App. Ser. No. 10/102,170, filed on Mar. 19, 2002 (now abandoned).

TECHNICAL FIELD OF THE INVENTION

The present invention, in general, is directed to a goniometer,preferably for use in an automated apparatus for testing and sortingoptical filters.

BACKGROUND OF THE INVENTION

Commercially-available optical filters are used for various purposes.For example, in U.S. Pat. No. 6,141,469 to Kashyap, there is disclosed amultiple band pass optical filter that may be used in a wavelengthdivision multiplexed (“WDM”) communication system to filter individualWDM channels. U.S. Pat. No. 6,169,828 B1 to Cao, also relating to anoptical filter, discloses a dense wavelength division multiplexer(“DWDM”) for use in a fiber optic network. Various optical filters arewell known to those skilled in the art.

Current methods of manufacturing such optical filters involve manuallymoving trays of optical filters, from the manufacturing station to afilter-testing station, and then manually testing each filter one at atime. An operator must manually pick a filter from the transfer tray,place it in a testing jig, align the filter in the jig either manuallyor automatically, test it with a laser and detector system, remove itfrom the jig, and place it back into the transfer tray. This process isunsatisfactory because it is very slow and prone to human error. Typicalthroughput is only 20-100 filters per hour.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, a principal object of the invention is to automate thetesting, characterization and sorting of optical filters, resulting inlower labor costs than presently possible, at increased production andproduct-quality levels.

These and other objects of the present invention will become readilyapparent to those skilled in the art after reviewing the followingsummary.

One aspect or feature of the present invention may be summarized as agoniometer preferably for use with an apparatus for translating opticalfilters. The optical filter-translating apparatus comprises a gantrysystem supported on a base or floor. The gantry system includes astructure translatable in the X and Y directions relative to the base.The optical filter-translating apparatus further comprises a supportmounted on the structure as well as a translatable platform disposedadjacent the structure. The support is translatable in the Z directionrelative to the base. The optical filter-translating apparatus furthercomprises a flexure mounted on the platform, a probe assembly mounted onthe support, and a light-directing element. The flexure is adapted toretain one of the optical filters. Translation of the platform causesthe platform-mounted flexure to be translated from a first X, Y and Zposition relative to the base to a second X, Y and Z position relativeto the base. The probe assembly is adapted to pick up one of the opticalfilters from a third X, Y and Z position relative to the base andtranslate the picked-up optical filter to the first position forretention of the picked-up filter by the flexure. The light-directingelement is supported by the goniometer and disposed adjacent the secondposition, is optically connected to a laser light source, and is adaptedto direct coherent light at an angle that is normal to theflexure-retained optical filter which has been translated by theplatform to the second position for testing the optical filter. For theoptical filter-translating apparatus, a preferred light-directingelement is a collimator.

Another aspect or feature of the present invention may be summarized asa goniometer comprising a base, a compound member supported by the base,and a light-directing element. The light-directing element (again,preferably a collimator) is operably mounted on the compound member, isoptically connected to a coherent light source (e.g. a laser), and isdisposed toward an optical filter. The goniometer further comprises afirst actuator and a second actuator. The first actuator is disposedalong a first axis and is operably coupled to the base for translatingthe light-directing element along a first arcuate path disposed in afirst plane. The second actuator is disposed along a second axis and isoperably coupled to the compound member for translating thelight-directing element along a second arcuate path that is disposed ina second plane. The first plane is orthogonal to the second plane. Thefirst and second axes are preferably coplanar. In operation, thecoherent-light source, thus mounted on the base, and in cooperation withthe actuators, is adapted to direct coherent light at an angle that isnormal to the optical filter that is being tested.

In the above-mentioned goniometer, the base preferably includes a pairof spaced-apart so-called “tip-axis” base plates and a channeled guidemember disposed therebetween. The compound member preferably comprises apair of spaced-apart so-called “tilt-axis” side plates as well as atilt-axis mount disposed therebetween. The goniometer also preferablyincludes a first gear set operably coupled between the first actuatorand the base, and a second gear set operably coupled between the secondactuator and the compound member. The light-directing element ispreferably a collimator, and the first and second actuators arepreferably DC motors.

When a plurality of goniometers are involved, the apparatus for testingoptical filters preferably further includes a coherent-light splitterwhich is optically connected between the coherent light source and eachassociated one of the corresponding plurality of light-directingelements, for splitting the coherent light from the coherent lightsource and passing the split coherent light to each of the plurallight-directing elements. Each light-directing element is adapted todirect coherent light at an angle that is normal to its associatedoptical filter. The apparatus for testing optical filters preferablyalso includes a corresponding plurality of reflected-light circulators.Each reflected-light circulator is operably connected between thecoherent-light splitter and a corresponding one of the plurallight-directing elements, and each reflected-light circulator is adaptedto receive reflected light from its associated optical filter that isbeing tested. The apparatus for testing optical filters furtherpreferably includes a corresponding plurality of sensor modules. In thisregard, each sensor module is operably connected to an associated one ofthe plural reflected-light circulators for characterizing eachassociated one of the tested optical filters in response to thereflected light that is received by the associated reflected-lightcirculator.

BRIEF DESCRIPTION OF THE DRAWINGS

A clear understanding of the various advantages and features of thepresent invention, as well as the construction and operation ofconventional components and mechanisms associated with the presentinvention, will become more readily apparent by referring to theexemplary, and therefore non-limiting, embodiments illustrated in thefollowing drawings which accompany and form a part of this patentspecification.

FIG. 1 is a system overview, in perspective, of the automated apparatusfor testing optical filters of the present invention;

FIG. 2 is a plan view of the system overview shown in FIG. 1;

FIG. 2A is a cross sectional view of a gel pack tray as it is disposedin a vacuum mount wherein the sectional view is taken at Section 2—2 inFIG. 2;

FIG. 3, a partially fragmented view in perspective, depicts a portion ofthe optical filter-testing apparatus, on an enlarged scale relative toFIGS. 1 and 2;

FIG. 4 is an exploded perspective view of the components of an elementof the optical filter-testing apparatus shown in FIG. 3 on an enlargedscale relative thereto;

FIGS. 5A and 5B are sequenced, sectional views depicting relativemovement of the components of the element shown in FIG. 4 on an enlargedscale relative thereto taken along the central longitudinal axis (“Z” inFIG. 3) at Section 5—5;

FIG. 6 is a perspective view of a lift pin assembly feature of theinvention;

FIG. 6A is an auxiliary partially-fragmented side elevational view,showing the relationship of certain elements or components not otherwiseviewable from FIG. 6;

FIG. 7 is a partially-fragmented side elevational view depictingportions of the automated filter-testing apparatus shown in FIG. 1 on anenlarged scale relative thereto;

FIGS. 8A and 8B are sequenced and partially-fragmented side elevationalviews, depicting operation of the filter lift pin assembly of FIG. 6;

FIGS. 8C and 8D are partially-fragmented side elevation views of theprobe tip, the lift pin, the tape and a filter illustrating how thefilter is partially released from the tape as it is raised by the liftpin;

FIGS. 9A and 9B are sequenced and partially-fragmented perspectiveviews, depicting an aspect or feature of the present invention which isalso shown in FIG. 3, and on an enlarged scale relative thereto;

FIGS. 10A and 10B are sequenced, partially-fragmented plan views,depicting a detail of the invention shown in FIGS. 9A and 9B, on anenlarged scale relative thereto;

FIG. 11 is a perspective view of an element or component of theinvention and which is shown in FIGS. 9A and 9B, on an enlarged scalerelative thereto;

FIG. 12 is a plan view, generally depicting certain elements orcomponents of the invention that are also generally shown in FIGS. 3 and7;

FIG. 13 is a partially-fragmented perspective view, depicting yet otherelements or components of the invention shown in FIG. 3, on an enlargedscale relative thereto;

FIG. 14 is a partially-fragmented perspective view depicting yet anotheraspect or feature of the present invention which appears in thebackground in FIG. 3;

FIG. 15 is a partially-fragmented perspective view of a preferredembodiment of the aspect or feature shown in FIG. 14, on an enlargedscale relative thereto;

FIG. 16 is a partially-fragmented side elevational view, taken generallyalong the plane 16—16 in FIG. 15;

FIG. 17 is a partially-fragmented side elevational view, taken generallyalong the plane 17—17 in FIG. 15;

FIG. 17A is an auxiliary view, in exploded perspective, taken from thebackside of FIG. 17 and depicting some features or aspects not otherwiseseen in FIG. 17;

FIG. 18 is a perspective view of a translation assembly shown in FIG.14, on an enlarged scale relative thereto;

FIG. 19 is a schematic illustrating a laser beam-splitting feature ofthe optics design of the present invention;

FIG. 20 is a schematic based on FIG. 19;

FIGS. 21A, 21B an 21C together provide a flow chart of a preferredmethod for testing optical filters;

FIG. 22 is a cross sectional view of a filter nest and flexure;

FIG. 23 is a perspective view of an aperture mask;

FIG. 24 is a top view of the rotating table illustrating the stop blockthat limits the rotation of the table and the switches that provide anindication of its position;

FIG. 25 is a side view of the rotating table of FIG. 24 showing the stopblock and features of the limit switches and their actuating flags; and

FIG. 26 is a perspective view of the flexure actuator and the vacuumpost.

Throughout the drawings, like reference numerals refer to like parts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially to FIGS. 1 and 2, which depict a system overview ofthe automated apparatus for testing optical filters, there is shown an“X” gantry system 100, 100A and 100B; a “Y” gantry system 102, 102A and102B; and a “Z” translator system 104, all of which systems arecommercially-available devices, wherein the various components and/orelements of which systems are generally translatable in the “X,” “Y”and/or “Z” directions relative to a base or floor 103. In particular,included with the “X” direction gantry system is an elongated “X” gantrysupport beam 100B that provides support for a generally U-shaped “X”gantry transverse-motion platform 100A on which an “X” gantry stage 100is longitudinally disposed and slideably mounted.

Also shown is a conventional “X” axis cable protector 101A disposedgenerally above the “X” gantry system 100, 100A and 100B as well as aconventional “Y” axis cable protector 101B for the “Y” gantry system102, 102A and 102B. Included with the “Y” gantry system 102, 102A and102B is a pair of spaced-apart elongated “Y” gantry system support beams102B (one of which is shown in the background) which are disposed on thefloor or platform 103. The illustrated background floor-support beam102B has fixedly mounted thereon one of a spaced-apart pair of elongatedgantry rails 102A on which the “Y” gantry platform 102 is longitudinallydisposed and slideably mounted. In reference to the “Y” gantry system,the foreground floor-support arrangement (not visible in FIG. 1 becauseof foreground structure) is similarly arranged. Preferably, the “X”gantry transverse-motion support beam 100B and spaced-apart “Y” gantrylongitudinal rails 102A are mutually perpendicularly disposed.

In general, the “X” and “Y” gantry systems (FIG. 1), which arecharacterized as servo-controlled, are each provided with conventionalhigh-speed closed-loop feedback systems adapted to translate the variouselements and/or components of the apparatus for testing optical filters(of the present invention) along the “X” axis, the “Y” axis, the “Z”axis and to rotate those filters about the “theta” axis, as disclosedherein.

In operation, the “X” gantry system 100, 100A and 100B translates the“Z” translator system 104 along the “X” axis, while the “Y” gantrysystem 102, 102A and 102B translates the “Z” translator system 104 alongthe “Y” axis, enabling the operative portion of the “Z” translatorsystem 104 to access the plurality of optical filters that are disposedon a UV-releasable adhesive tape 108 stretched on a hoop or frame 111,as shown in FIGS. 8A and 8B on optical filter-input or filter-receivingplatform or table 110 and, after testing such optical filters, totransfer the tested optical filters to an assortment oftested-and-sorted optical filter classification trays 112 (shown as afour-by-four array of trays in FIGS. 1 and 2) which are located at afilter-output or filter-dispatch platform or table 114. TheUV-releasable tape 108 may be purchased from Fitel Technologies(formerly Furukawa Electric Co.), as tape number UC-120M-120 (anon-expandable tape) or UC-353EP-110 (an expandable tape). Both tapesare low-tack UV-release tapes that are typically used in wafer-dicingapplications.

Alternatively, optical filters can be supported in gel packs or vacuumrelease trays that are disposed on filter receiving table 110. Thesetrays are supported in specially configured vacuum mounts 700 located ontable 110.

Referring to FIG. 2A, vacuum release trays 702 are placed in vacuummounts 700 on an O-ring seal 704. The O-ring seals against both thebottom of the tray and the mount itself to form a vacuum chamber 703defined by the bottom surface of the tray, the O-ring and the mount. Twogrooves 706 extend from the O-ring inwardly to a vacuum port 708. Thevacuum port 708 extends through the table 110 to a vacuum fitting 710disposed on the bottom surface of table 110. A vacuum is selectivelyapplied to the vacuum fitting to suck air out of the chamber 703. Thisreduction in pressure in the chamber 703 both holds the tray 702 inmount 700 and weakens the grip trays 702 have on filters 196.

As background information, the optical filter array or tray, beforebeing placed by hand or machine as desired onto the filter-receivingtable 110, were formed at a prior station (not shown) where a glasssubstrate with an optical coating (also not shown) was divided intoindividual optical filters 196.

Referring next to FIG. 3, the “Z” translator system 104 includes atheta-axis stage 116 mounted on a “Z” axis stage 118 via bracket 126.Theta stage 116 is a motor having an output shaft 168 that is rotatableto predetermined angular positions under computer control. This stage istermed the “theta-axis” stage since it rotates the probe to an angletheta about an axis that is disposed parallel to the “Z” direction oraxis (i.e. vertically) and passes through the center of stage 116. Thetheta axis therefore translates with the theta stage and (in thepreferred embodiment) extends through the longitudinal centerline of theprobe assembly. The theta stage may be characterized as aservo-controlled axis.

The tray-handling end effector cylinder 119 is connected to bracket 126via bracket 125 to enable the tray-handling end effector 120 which iscoupled to the end of the moveable rod of cylinder 119 to extend andretract along (preferably in non-rotative relationship relative to) afirst vertical axis Z1—Z1 relative to the optical filters at the inputplatform 110 and/or the output platform 114. The “Z” translator system104 further includes a standard machine vision camera 121 (FIG. 3), toenable accessing the optical filters at the filter-input platform 110and, after testing such optical filters, to enable transferring thetested filters to the filter-output platform 114. The camera is alsocoupled to “Z” axis stage 118.

The tray-handling effector 120 includes tines or fingers 122 operablymounted on the effector 120 for grasping and retrieving the opticalfilter-carrying trays 112 at the output platform 114 and fortransferring such trays, after filter testing, to a front row depot.This depot, identified in FIGS. 1 and 2 as row 150 is used for storingempty trays, completed trays of tests and lids for trays that can beaccessed both to replenish depleted tests, replace depleted input testtrays and to remove completed test tray and replace them with emptytrays. The effector 120 is configured to drive fingers 122 apart ortogether to selectively grasp or release the individual trays undercomputer control.

The “Z” translator system 104 further includes a filter-capture endeffector 124, also generally referred to within this patentspecification either as the vacuum probe assembly or as “the head” 124,which is mounted on the rotatable output shaft 168 of theta stage 116which is mounted on Z translator system 104, which, in turn, is operablyaffixed to the moveable “X” gantry stage 100 (FIG. 1), to enable thevacuum probe assembly or head 124 to move up and down along (and rotateabout) a second vertical axis Z2—Z2 (FIG. 3). Vertical axis Z2—Z2 isparallel to the “Z” axis.

Referring to FIG. 4, the vacuum probe assembly or head 124 includes agenerally cylindrical and elongated sleeve 128, which defines a blindhole 130 (FIG. 5A) into which an elongated vacuum probe 152 is disposed.This probe is slidably received in through blind hole 130 in which it issupported.

The vacuum probe assembly or head 124 further includes a generallycylindrical collar clamp 142 also defining a through bore 144. Thecylindrical collar clamp 142, in turn, defines a radially-disposedthrough-slot 146. The illustrated clamp 142 further includes atransversely offset threaded fastener 148, for enabling the cylindricalsleeve 128 and the cylindrical collar clamp 142 to be removably affixedtogether in a conventional manner. The cylindrical sleeve 128 alsodefines a cylindrical neck portion 150, of reduced outer diameterrelative to the outer diameter of the cylindrical sleeve 128, forenabling the cylindrical neck portion 150 of sleeve 128 to be snugglyengageable within, and readily removable from, the through bore 144 ofthe cylindrical collar clamp 142 in a conventional manner.

Shaft 168 (FIG. 5A), to which neck portion 150 is attached by clamp 142,defines an axially disposed internal fluid passageway 170 (shown inphantom line in FIGS. 5A and 5B).

The vacuum probe assembly or head 124 also includes a generallycylindrical alignment clamp 174, which defines a radially disposed slot176 and a central through bore 178. The inner diameter of the alignmentclamp through bore is so matched relative to the outer diameter of thelower cylindrical band 172 of vacuum probe 152 as to enable thecylindrical band 172 to be snugly disposable into the alignment clampthrough bore 178. The illustrated alignment clamp 174 further includes aconventional threaded fastener 180 located adjacent to the through bore178 and disposed transverse to the radial slot 176 for releasablyaffixing alignment clamp 174 onto the cylindrical band 172 of thegenerally cylindrical and elongated vacuum probe 152 in a conventionalmanner.

The alignment clamp further defines an axially disposed, stepped bore182 (FIG. 5A) spaced from the through bore 178, into which stepped bore182 a matched stepped threaded fastener 184 (which functions as aspacer) is disposed. An end portion 186 of spacer 184 is threaded, andcylindrical outer sleeve 128 defines a threaded bore (FIGS. 5A and 5B)having threads that mate with the end portion 186 of fastener 184.

The cylindrical outer sleeve 128 further defines a transversely disposedand threaded side bore 190 of substantially identical inner diameter asa similar transversely disposed and threaded side bore 188. These twobores are configured to receive threaded vacuum fittings, and arefluidly coupled together with a length of flexible tubing 189. The innerend of bore 190 is in fluid communication with passageway 170 since bothopen into a chamber 191 defined at the upper end of sleeve 128 locatedbetween the sleeve and the lower end of shaft 168.

Side bore 188 of probe 152 is in fluid communication with an axiallyoriented intermediate fluid passageway 166. Probe 152 also includes athreaded plug 162 disposed in the upper portion of bore 154 (FIGS. 5Aand 5B) and providing a fluid tight seal thereat. Probe 152 defines anaxially aligned orifice 164, which is in fluid communication with bore154 via an intermediate fluid passageway 166.

Flexible tubing 189 is configured to permit probe 152 to slide up anddown within sleeve 128.

When a vacuum is drawn by conventional means to impose vacuum at innerpassageway 170, this vacuum is communicated to bore 190, through thelength of flexible tubing and through bore 188. The vacuum is thencommunicated through intermediate fluid passageway 166 and thence toorifice 164.

In operation, downwardly disposed member 168 is axially advanced towardan optical filter 196 (shown in phantom line in FIGS. 5A and 5B), forenabling the orifice 164 of the vacuum probe 152 to contact the opticalfilter 196.

Sufficient vacuum is imposed at fluid passageway 170 to enable theoptical filter 196 to be held by the orifice 164, after the opticalfilter 196. When the orifice 164 initially makes contact with theoptical filter 196, vacuum probe 152 moves axially upward relative tosleeve 128, sliding upward within sleeve 128 into blind hole 130.

By permitting probe 152 to “collapse” the length of the probe assemblyon initial contact with the filter, the risk of damage to the filter issubstantially reduced by providing a soft landing for advancing vacuumprobe 152. A soft landing is insured but only until alignment clamp 174abuttingly engages the cylindrical outer sleeve 128. This abuttingrelationship is shown in FIG. 5B. For this reason, the system isconfigured to stop the downward advance of the “Z” stage (to which probeassembly or head 124 is mounted) before clamp 174 abuts sleeve 128. Inan alternative embodiment, individual filters can be selected from anyof the gel trays 702 that are held in vacuum tray mounts 700 (FIGS. 1, 2and 2A).

Referring back to FIGS. 1 and 2, the “X” gantry system 100, 100A and100B translates the head 124 along the “X” axis while the “Y” gantrysystem 102, 102A and 102B translates the head 124 along the “Y” axis, toenable the head 124 to be moved to any point in the X-Y plane, so thatthe head 124 can access optical filters on the filter-input platform 110and, after testing and sorting the optical filters, thereafter transfertested-and-sorted optical filters wherever desired onto output platform114.

Reference is next invited to FIGS. 6, 6A, 7, 8A and 8B, to discuss a“pick and place” procedure as well as a filter lift pin assembly 200(FIG. 6), both of which are additional features of the presentinvention. The filter lift pin assembly 200 (not visible in FIG. 1) islocated generally beneath the optical filter input platform 110 shown inFIG. 1. The optical filter lift pin assembly 200 includes a base 202, aguide bracket 204 mounted on the base 202, and a pneumatic cylinder 206spaced in distal relation to the bracket 204.

The pneumatic cylinder 206, also mounted on the base 202 via a chamberedalignment block 208, is operably connected via a piston rod 210 to awedge 212. The guide bracket 204 includes an upper surface 214, whichdefines an aperture through which a filter lift pin 216 and a pin guidebushing 218 are disposed. Pin 216, disposed through the through bore ofpin guide bushing 218, is urged downwardly into sliding engagement withthe wedge 212 by a helical spring 217 which is captively retained by thepin 216, as is shown in FIG. 6A. An upper surface of wedge 212, on whichlift pin 216 rests, is inclined relative to precision linear slide 219fixed to the base 202.

The pneumatic cylinder 206 operates in a conventional manner to extendand retract the piston rod 210 along the axis X1—X1 (which is parallelto the “X” axis). Such reciprocal action, in turn, causes the lift pin216 to extend upward or retract downward relative to the base 202 andthe bracket upper surface 214. The axis of pin extension and retractionis parallel to the “Z” axis.

Wedge 212 is supported on and fixed to the upper translating portion 225of linear slide 219 by conventional threaded fasteners 221. The lowerfixed portion 227 of linear slide 219 is fixed to base 202 by fasteners223. See FIG. 6A.

Linear slide 219 is preferably a conventional precision slide that usesrecirculating ball bearings between the upper translating portion 225and the lower fixed portion 227 of slide 219. By using slide 219,reduced friction translation of wedge 212 is provided when moving from apin 216 down position to a pin 216 up position and vice versa.

To achieve precision movement of the wedge 212 in this regard, the liftpin assembly 200 further includes a wedge-extension flow-control device220, which is operably coupled to pneumatic cylinder 206 via a chamberedright-angled pneumatic fitting 240, as well as a wedge-retractionflow-control device 222, which is mounted directly on the pneumaticcylinder 206.

A spool-shaped coupling 224 is threaded onto the free end of rod 210 tomechanically couple the free end of the rod to wedge 212. The spool islocked onto rod 210 by a jam nut 229 that is also threaded onto the freeend of rod 210 and is tightened against spool 224 to hold it in place.The spool, in turn, is disposed in a downwardly-facing slot 231 formedin a downwardly-facing surface of wedge 212. A small cylindrical gap isprovided between the spool and the wedge to permit slight misalignmentbetween the cylinder and the wedge. This gap permits a slight lateraland vertical misalignment of the wedge and cylinder to exist withoutcausing the rod to bind in the cylinder.

Control devices 220 and 222 are each connected to the pneumatic cylinder206 (as described above) and separately via conventional fittings 244and 245 and via conduits 226 and 227 to a flow-control fluid source (notshown) in a conventional manner.

As is shown in the foreground in FIG. 6, the filter lift pin assembly200 further includes an optical lift pin extension sensor 228 mounted onthe base 202 and disposed transverse to the piston rod 210. Not visiblein FIG. 6 but located behind the guide bracket 204 is a secondextension/retraction sensor that is similarly disposed transverse to thepiston rod 210. As is shown in the foreground in FIG. 6, the wedge 212defines a lateral finger 230, and the foreground-mounted lift pinextension sensor 228 includes an end portion 232 defining a U-shapedslot through which the lateral finger 230 is passed for sensingextension or retraction of the pin 216 relative to the base 202. Thewedge 212 further includes a similar lateral finger (not visible in FIG.6, as it is hidden behind the guide bracket 204); and thebackground-mounted lift pin extension sensor (not visible in FIG. 6)similarly includes an end portion (not visible in FIG. 6) defining aU-shaped slot through which the background lateral finger is similarlypassed for sensing extension or retraction of the pin 216 relative tothe base 202. To provide adjustment of the guide bracket 204 as well asthe extension sensors 228 along the upper surface of the base 202, theguide bracket 204 and extension sensor 228 (as is shown for theforeground sensor) are respectively provided with conventional threadedfasteners 234 and 235.

In operation, the piston rod 210, spaced above and parallel to base 202,is caused to move relative to the base 202, for causing the opticalfilter lift pin 216 to extend toward or retract from platform or table110 and tape 108 in frame 111, as shown in FIG. 7. More particularly, asthe lift pin 216 contacts the underside of adhesive tape 108, the tape108 as well as the optical filters 196 adhesively held thereon are urgedslightly upwardly, toward the machine vision camera 121 and the head124, as shown in FIGS. 8A and 8B, to help break the adhesive bondbetween the filter 196 and the tape 108.

As shown in FIG. 8C, each filter is in substantial complete contact withadhesive tape 108 when the tape is relaxed. FIG. 8D, however,illustrates how the tape-to-filter relationship changes when lift pin216 deflects tape 108 upwards. As tape 108 is forced upward by pin 216,it causes the contact area between the tape and the filter to bereduced. The tape is deformed over the radiused tip 233 of pin 216,causing it to form a curved surface. The formation of this curvedsurface causes the portions of the tape that were previously adhered tothe filter (as shown in FIG. 8C, to pull away from the filter. As aresult, the area of the filter that is adhesively attached to the tapeis significantly reduced and the filter, when grasped and pulled awayfrom the tape by probe 152 will release from the tape more gently andwith reduced force.

Note that the degree of deflection provided by lift pin 216 in FIG. 8Dand the degree that the tape is curved due to pin 216 has beendeliberately exaggerated to make the reduced contact area between tape108 and filter 196 more apparent.

The machine vision camera 121, fixedly mounted to the “Z” axis stage 118and to the “X” gantry stage 100, is in parallel relation to head 124;and the “Z” axis stage 118 is laterally translatable along “X” gantrysupport beam 100B, as shown in FIG. 7. As described above in regard toFIG. 1, the “Y” gantry platform 102 is also movable along “Y” gantrybeams to provide motion of the “Z” axis stage 118 in a direction that isorthogonal to the “X” direction motion provided by the “X” gantry stage.Thus, the system is configured to move the “Z” axis stage 118 in boththe “X” and the “Y” direction under computer control. The head 124 picksup optical filters 196 (FIGS. 8A-D) and places them in proper positionin individual nests 236 of a rotary processing table 238 (FIGS. 3 and 7)to be tested individually. In general, the head 124 first picks upoptical filters 196 individually from the input tape frame 111 (or thevacuum release trays 702) and then, after the filters have beenoptically tested, places the tested optical filters 196 individuallyinto filter classification trays 112, as shown in FIGS. 1, 2, 3 and 13.

The base 202 of the filter lift pin assembly 200 is fixedly mounted on aseparate “X” direction translation device 242 and a “Y” directiontranslation device 243 (FIG. 7) for moving the filter lift pin assembly200 across the base 103 relative to the input table 110 and the inputtape frame 111. The two devices 242 and 243 permit the filter lift pinassembly to be moved in both the “X” and the “Y” direction and therebypositioned under any filter 196 on adhesive tape 108. These two devicesoperate under computer control to permit lift pin 216 to be locatedunder and to lift any of filters 196 under computer control. Translationdevices 242 and 243 are preferably linear electrical motors configuredto be operated under computer control.

The machine vision camera 121 (FIGS. 3 and 7) has a collimated field ofview for viewing and locating the optical filters 196 to be picked up.The camera 121 and head 124 are spaced in parallel relation. Head 124 ismoved by the “X” and “Y” gantry systems in response to informationprovided by the machine vision camera 121, so that the head 124 islocated directly above one optical filter 196 to be picked up.

After being vertically aligned above such optical filter 196, the “Z”axis stage 118 (FIG. 7) is then actuated causing head 124 and vacuumprobe 152 (FIGS. 8A and 8B) to extend downwardly to contact such opticalfilter 196. Downward movement of the head 124 is generally completedbefore the outer sleeve 128 of head 124 contacts the alignment clamp 174(which is shown in FIG. 5B) to avoid damaging the optical filters 196.In addition, the “Z” stage is also provided with sufficient extra travelsuch that it does not reach the end of its travel before vacuum probe152 contacts filter 196, but has a comfortable margin of extra motionavailable. This margin will, of course, be determined on a case-by-casebasis depending upon the particular geometry of the machine.

Once the probe 152 and filter 196 make contact, a vacuum is applied toorifice 164 and hence to filter 196. Optical filter lift pin 216 is thenraised upwardly until it is in the position shown in FIG. 8C. At thispoint, the filter is captive between pin 216 and probe 152.

Pin 216 continues moving upward causing the adhesive tape to deflectupwardly and bend around the radiused tip of lift pin 216, therebyreducing the area of adhesion between filter 196 and the adhesive tapeas described above.

At the same time lift pin is deflecting the tape upwardly, it is alsomoving the desired filter 196 upwardly and is collapsing vacuum probe152 into sleeve 128 as shown in FIG. 8D.

Next, the head 124 is retracted upwardly by operation of the “Z” axisstage 118, causing the head 124 to be lifted above the table 110 andframe 111. As probe 152 is lifted, it pulls filter 196 away from theremaining portion of adhesive tape holding filter 196 to the adhesivetape by way of the vacuum applied to the top of filter 196. Once free ofthe surface with the filter attached to the end of the probe the “X” and“Y” gantry systems translate head 124 and hence filter 196 in both the“X” and the “Y” directions above processing table 238, as shown in FIG.7. In general, this “pick and place” procedure is repeated until each ofthe four forward most nests 236 of processing table 238 is provided withan optical filter 196 for testing.

To insure that the probe is accurately positioned with respect to thefilter, a calibration routine is performed in which errors ormisalignments of the probe with respect to the camera 121 aredetermined.

As described above, the position of the filter is determined based uponthe position of the camera (indicated by the drive signals applied tothe “X” and “Y” stages when the filter is in the camera's field of view)and by the offset of the filter within the camera image.

The absolute position of the filter is determined by summing these twovalues.

As described above, once the position of the filter is determined, theprobe must be moved to a precise position above the filter in order tocontact and pick up the filter.

In order to position the probe accurately above the filter, the distancebetween the probe tip and the camera must also be known, for the “X” and“Y” stages must be moved this distance in order to locate the probeabove the filter.

The camera-to-probe distance, however, can be known only approximatelybased solely upon the dimensions (and their associated dimensionalerrors) of the parts located between the probe tip and the camera.

The dimensional errors refers to errors in manufacturing and assemblingthe probe tip, the probe sleeve in which the tip is inserted, the“theta” stage motor that supports and rotates the probe, the rotatingshaft in the theta stage, the theta stage motor mounts and the locationof the theta stage mounting holes with respect to the camera mountingholes, among others.

Errors in any of these dimensions are additive and provide a relativelylarge circle of positional uncertainty of the probe with respect to thecamera.

To eliminate this error, one might manufacture or purchase extremelyaccurate components and provide extremely precise adjustment features.This, however, would be prohibitively expensive. An alternativeapproach, and the one employed by the present invention, is to firstdetermine the location of a feature (a corner of the touch-off block)using the camera and then again determine the location of the corner ofthe touch-off block, but this time by making electrical contact, usingthe probe, with each of the two edges that intersect at the corner thatwas located by the camera. Since both locations use the same frame ofreference (the X, Y gantry), the offset between the camera and probe canbe calculated by simply subtracting the corresponding X and Y values.

The first step is to pre-position the camera over the corner of thetouch-off block so that the corner is in the field of the view. This isdone one time when the machine is first set up and the coordinates aresaved. After going to the pre-position, the computer finds the cornerand records the x and y coordinates of the corner relative to the centerof the camera.

Next, the probe is pre-positioned near the touch-off block in x, y and zfor performing the “touch-off” in the “y” direction. This is done onetime when the machine is first set up and the coordinates are saved. Thesame procedure is repeated for “touchoff” in the “x” direction. The“touch-off” procedure. The probe is (1) rotated using the “theta” stageto a first predetermined angle, (2) moved until it contacts firstsurface 5000 of touch-off block 5002 as indicated by a contact sensorconnected to the computer and (3) a record of its position is made bythe computer.

In the preferred embodiment, the sensor is a single digital signal linewith a pull-up that is coupled to the computer. The digital signal lineis coupled to the touch-off block, which is electrically isolate fromthe structure to which it is mounted. As a result, as long as the probe,which is grounded, is not contacting the touch-off block, the signal onthe signal line will be pulled up to a logical “1”. The moment the probecontacts the touch-off block, the pull-up will be grounded and thesignal on the signal line will be a logic “0”. The touch-off block ismade of a conductive metal. Therefore, whenever the probe touches thetouch-off block, the signal on the signal line goes from a logical “1”to a logical “0”.

The computer signals the “X” stage to move the probe in the “X”direction very slowly (approximately 0.01 in/sec) until the sensorsignal goes to logical “0”. Once the signal goes to a logical “0”, theposition of the probe (as a function of the position of the “X” stage)is recorded.

The probe is then backed away from the block in the “X” direction,rotated to a second predetermined angle (preferably 90 degrees from thefirst predetermined angle) and the incremental moving, touching andrecording steps are repeated.

The probe is again backed away from the block in the “X” directionagain, rotated to a third predetermined angle (preferably 180 degreesfrom the first predetermined angle) and the touching and recording stepsare repeated again.

If the probe were perfectly symmetric and centered about the rotationalaxis of the theta stage, each of these three positions would be thesame. As a practical matter, however, there will be a small butsignificant off-center rotation of the probe when the theta stage (towhich it is attached) rotates.

As a result, the true position of the probe with respect to the surfaceit touches, and hence the true position of the probe with respect to thecamera will vary depending upon the rotational position of the thetastage.

For convenience in calculating the offset, the offset can be broken downinto two components: (1) a combination of a fixed offset distance fromthe camera to the center of rotation of the theta axis, plus (2) anadditional offset due to the misaligned and off-center coupling of theprobe to the rotating shaft of the theta stage.

For this reason, the computer calculates these two offsets (one fixedand invariant, the other a function of the rotational position of theprobe) and saves them for later use when positioning the probe in aspecific rotational position near a filter.

These two offsets (fixed and rotational) are used (1) to position theprobe over a gel pack or tape frame when the probe picks up a filter,(2) to position the probe with attached filter over a flexure beforeplacing it in the flexure, (3) to position the probe over a flexurebefore picking up the filter, and (4) to position the probe over theappropriate sorting tray before depositing a tested filter in one of thesorting trays.

It should be clear that the calibration process described above onlyprovides the probe offset from the camera to the probe in a singledirection: the direction perpendicular to the surface of the touch offblock that it contacts. Since the contact was made with surface 5000 ofthe touch-off block and since this surface is perpendicular to the “X”direction of travel, this calibration method will only provide a truemeasure of the camera-to-probe distance in the “X” direction using the“X” stage.

The probe is also moved in the “Y” direction using the “Y” stage andtherefore the same calibration process is used to determine a fixed androtational offset in the “Y” direction by touching the probe three moretimes as described above, but this time against surface 5004 which isperpendicular to the “Y” direction of travel.

At the end of this process, the system has determined a fixed, (i.e.rotationally independent) “X” and “Y” offset of the probe with respectto the camera and has also determined a rotational “X” and “Y” offsetthat is a function of the rotational position of the probe provided bythe theta stage. Whenever the probe is rotated to particular angle,either for picking up a part or for placing a part, the proper “X” and“Y” positions of the “X” and “Y” stages are calculated to take therotational offset into account.

In an alternative embodiment, a table (or tables) of pairs of “X” and“Y” offsets versus probe rotational positions may be calculated aftercalibration and used during all subsequent pick and place probeoperations. In this manner, one can eliminate the repetitive calculationof “X” and “Y” offsets based on new rotational positions that wouldotherwise be required every time the probe is rotated.

Calibrating for the Post Height:

Just as the system need to know the “X” and “Y” offsets of the probewith respect to the camera, it similarly needs to know the location ofpost 512 (SEE FIG. 9A) with respect to the probe the “Z” direction. Aseparate calibration process is performed to determine this distance.

As described above, when probe approaches each of the flexures to eitherpick or place a filter, it moves downward until the filter ismechanically held between the post and the probe tip with a slightcompression of the probe tip within its sleeve. Once in this position,the filter is securely held on its top and bottom planar surfaces by theprobe and the post. The flexures can be moved or vacuum turned on or offwithout the risk that the filter will be accidentally ejected from themachine.

An electrical potential is applied to the post, which is a conductivemetal. This potential may be always applied, or it may be selectivelyapplied via a computer-switched electrical connection coupled to thepost.

The post is first positioned by the linear motor 510 to the right (asviewed in FIG. 1) of rotary processing plate 238. The post is raisedinto position adjacent the bottom of a flexure, in the same position itwould be in when supporting a filter at a flexure.

The probe (which is coupled to the sensor circuit as described above) ismoved into position over the post at the flexure.

The probe is lowered by the computer which moves the “Z” stage downwardvery slowly (approximately 0.01 in/sec). The computer continuouslychecks the sensor signal line to see whether the probe has contacted thepost.

This process of lowering and checking continues until the probe touchesthe post. Once the probe touches the post, the signal line will go fromlogic “1” to logic “0” as electricity is communicated from the probe,through the post to electrical ground.

When the probe contacts the post, the system records the position of theprobe (as a function of the “Z” stage position).

Once the “Z” height of the post is recorded, it is used to determine theproper downward (“Z” direction) stopping point of the probe, based onthe thickness of the filter, when the probe is lowered into contact withthe filter.

For a filter having a nominal thickness “Q”, the probe is lowered to thecalibrated height (“Z” direction) of the post plus the thickness of thefilter, minus a small amount of desired probe compression in the probesleeve. These calculations are performed by the computer when it bringsthe probe downward in contact with the filter at each flexure location.

Calibrating the probe for Lift Pin Height:

In a similar fashion to the post height calibration, the lift pin heightmay also be calibrated.

A small fixture could be placed, temporarily, over the lift pin 216.This fixture would be connected to the touch-off circuit andelectrically insulated from the pin. The fixture would have a“touch-off” surface coplanar with end of the lift pin 216. A touch-offprocedure similar to that used for determining the post height can alsobe used for determining the height of the lift pin in its raisedposition. The lift pin height can be used to calculate the properlowered position of the probe over the tape frame when picking a filteroff the frame.

Reference is next directed to FIGS. 9A, 9B, 10A, 10B, 11, 12, 13, and 22to discuss an “automated material handling system,” which is yet anotheraspect or feature of the present invention. As mentioned above, the head124 picks up selected optical filters 196 individually from the inputtape frame 111 (FIGS. 8A and 8B) and the “X” and “Y” gantry systems areemployed to move the “Z” axis stage 118, that has been spaced above aselected nest 236 of the rotary processing table 238 (FIG. 7), so as toplace an optical filter 196 into each nest 236 for further opticalfilter processing. For this purpose, each nest 236 of the rotaryprocessing table 238 is provided with an individual flexure 250 (FIGS.3, 11 and 12) for holding a single optical filter 196.

The flexure 250 is generally elongated (FIG. 11), defining circularapertures 252 for fixedly mounting individual flexures 250 to the rotarytable 238. The flexure 250 also defines generally elongated and opposedapertures 254. The flexure 250 further defines a longitudinal slit 256that is generally disposed between the elongated apertures 254. Inparticular, the elongated apertures 254 are defined both by externalsidewalls 258 as well as by inner sidewalls 260 of the flexure 250. Theinner sidewalls 260, which form a portion of the elongated apertures254, straddle and define the slit 256. The external sidewalls 258 aswell as the inner sidewalls 260 are sufficiently dimensioned, in adirection transverse to the slit 256, and the material of flexure 250sufficiently elastically flexible or “springy” such that spaced-apartjaws 262, also defined by the flexure 250, repeatedly return to theiroriginal spacing, after being spread-apart by a small distance, asdescribed below.

The flexure is preferably a monolithic device manufactured out of asingle piece of metal such as steel, using electro-discharge machining(EDM) operations. Each of the inner and outer sidewalls is preferably ofsubstantially the same length and are substantially parallel therebydefining (together with the mounting portion 253 and the jaws 262) twoparallel four bar linkages.

Unlike common four bar linkages, in which there is a separate mechanicalcoupling at each of the junctions, the inner and outer sidewallselastically deform forming a slight “S” shape as each arm is moved awayfrom gap 256.

Each arm includes an inner and an outer sidewall that are ofsubstantially the same length and are substantially parallel. With thisarrangement, when the arms are deflected apart, they move apart withlimited rotation each moving along a short curvilinear path.

By constraining the motion of the free ends of the arms to curvilineartranslation, the lateral forces applied to open the arms issubstantially the same as the lateral force applied by the arms againstthe filter to hold the filter in place.

The thickness of the sidewalls (as measured in the “T” direction) ispreferably smaller than the height of the sidewalls (as measured in the“H” direction). To insure equal deflection of both arms when a force isapplied, the length of the sidewalls and their cross-sectional areas arepreferably the same and are constant over substantially their entirelength. In a typical flexure, the height of the sidewalls will bebetween 0.05 and 0.15 inches. The thickness of the sidewalls will be0.015 to 0.04 inches. The thickness to height ratio is preferablybetween 2 and 5. As this ratio increases, the arms become more stiff andresistant to deflections in the “H” direction, as compared to deflectionin the “T” direction.

The height to length ratio of the sidewalls of the flexures is a strongindicator of the flexure arms' resistance to bending in the “H”direction. If the arms were susceptible to bending either upward ordownward more than a tiny amount, the filters will not consistently beheld in a flat orientation—the position in which they need to be heldfor testing. Only a slight bending upward of one arm with respect to theother, on the order of an angle of 0.1 degrees or so, will cause thefilter to be twisted between the two arms (i.e. rotated about the “L”axis) by perhaps 5-20 degrees. This large twisting would requiresignificant (and slow) movement of the goniometers to find and move totheir proper perpendicular position with respect to the bottom surfaceof the (twisted) filter before testing can begin. For this reason, andgiven the specific requirements of this application, the length toheight ratio of the arms of the flexure is preferably at least 5 and nogreater than 50. More preferably, it is at least 8 and no greater than40. Even more preferably, it is at least 15 and no greater than 30.

The thickness to length ratio of the sidewalls of the flexures is astrong indicator of the sidewall's flexibility and ability of the armsto accommodate a wide variety of filter widths. As thelength-to-thickness ratio of the sidewalls decreases, the arms becomemore resistant to deflection in the “T” direction. The force required tospread the arms a specific distance apart increases. For a flexureadapted to hold optical filters (as the present flexures are), too greata force can crush the filter, yet too small a force will permit thefilter to fall out of the flexure. For this reason, the force to spreadthe arms of the flexure must be carefully tailored if the machine is toaccommodate a wide variety of filters having different widths withoutcrushing them. A preferred ratio length (“L” direction) to thickness(“T” direction) ratio for the sidewalls of the flexure is thereforepreferably between 25 and 300. More preferably it is between 40 and 200.Even more preferably it is between 55 and 140.

In FIG. 22, a typical flexure 250 is shown in its relationship to table238 and the particular filter nest 236 to which it is oriented. Threadedfasteners 2202 extend through the apertures 252 in the flexure and holdthe flexure to table 238. The arms of the flexure extend from the tabletoward and underneath nest 236 in close proximity thereto. Several ballbearings 2206 are located in a linear bearing race 2208 that is formedin the bottom of the filter nest to insure that the free ends of thearms are located at a precise distance away from the bottom of the nest.As shown in phantom lines in FIG. 10A, the bearing race 2208 extendssubstantially perpendicular to the longitudinal extent of arms andsubstantially parallel to the direction the arms travel when they aredeflected outwardly to receive the filter 196.

Each arm is supported on two ball bearings 2206 that are spaced apart inthe bearing race 2208 by ball guide 2210. These balls rest against flatbearing surface 2212 located on the back of each arm. When the arms aredeflected outward, spreading them to receive the filter, the ballbearings roll in the race as well as across bearing surface 2212 to keepthe arms at a constant angular relationship with respect to each otherand to keep them in the same plane. The flexure and the table arepreferably dimensioned such that the flexure, when attached to thetable, preloads the flexure arms against the ball bearings. In thismanner, the flexures make good contact with the ball bearings, and thepreload further reduces the likelihood that they will be lifted up awayfrom the bearings when the arms are spread apart to receive the filter.

Reference is next directed to FIGS. 3, 9A, 9B, 12 and 26 to discuss anactuator assembly 264 for the flexure 250 discussed above. The flexureactuator assembly 264 is fixedly mounted on pneumatically actuatedlinear stage 266. This stage is moved in a linear direction by apneumatic cylinder integral to stage 266 (not shown). Stage 266, inturn, is mounted on flexure actuator cylinder base 500. Base 500, inturn, is adjustably fixed to plate 502. Plate 502 is coupled to theoutput side of linear motor 510, which in turn is fixed to base 103.

Linear motor 510 is configured to translate plate 502 in the “X”direction. The components mounted on plate 502 are similarly translatedin the “X” direction whenever linear motor 510 moves. Translating stage266 moves flexure actuator assembly 264 in the “Y” direction (i.e.toward and away from a flexure) when air under pressure is applied totranslating stage 266.

The flexure actuator 264 includes a pair of spaced-apart rollers 274rotatably mounted on an upper portion 276 (FIGS. 10A and 10B) ofL-shaped member 269. By design, the rollers 274 move in a planecoinciding with a forward planar portion 280 (FIG. 10B) of flexure 250that defines the jaws 262. Also, the spacing of the rollers 274 is suchthat the rollers 274 cause the jaws 262 of flexure 250 to spread apartslightly, which in turn laterally opens the flexure's longitudinal slit256 slightly, after the rollers 274 are first aligned with the jaws 262(FIG. 10A) and thereafter brought into engagement with the jaws 262(FIG. 10B) by operation of pneumatic cylinder 270, as shown in FIG. 9B.Also by design, the L-shaped member 269 is so spaced in the “Z”direction relative to the nest 236 of processing table 238 as to achievesuch an effect.

For grasping a single optical filter 196, the forward portion 280 of theflexure 250 defines a gap 282 (FIG. 10A). The gap 282 is bounded on oneside by two adjacent fingers 283 and 284 that extend inwardly into gap282 from one jaw 262 of the flexure and on the other side by anotherfinger 286 that extends inwardly into gap 282 from the other jaw 262 ofthe flexure. The gap 282 is dimensioned relative to a single opticalfilter 196 to permit such optical filter 196 (when disposed in the planeof the forward portion 280 of flexure 250) to fit snugly into the gap282, after the jaws 262 have been spread slightly (as shown in FIG.10B), and thereafter to be held in place in the gap 282 by fingers 283and 284 and the finger 286 after the flexure actuator assembly 264 isretracted from the flexure 250. By providing these three points ofcontact, the filter is gripped consistently at three points on thecenterline of the filter: two points on one side of the (typicallyrectangular) filter and one point on the opposing side of the filter.This three-point contact assures accurate positioning and location ofthe filter and tolerates slight variations in straightness of theopposing sides it contacts.

In addition to supporting and positioning flexure actuator assembly 264,linear motor 510 also supports and positions a vacuum post 512. Thispost is positioned underneath gap 282 before filter 196 is inserted intogap 282. The post is positioned underneath filter 250 and adheres tofilter 196 using a vacuum applied to a hole that extends through thepost 512 to a vacuum port 513. A vacuum is selectively applied to port513 under computer control to provide or remove a vacuum at the top ofpost 512. Without this post, the flexure arms might knock the filter offthe bottom of vacuum probe 152 as they move in to contact and supportfilter 196.

Post 512 is configured to be raised and lowered slightly during thepositioning process. It is lowered under computer control wheneverlinear motor 510 moves in the “X” direction from flexure to flexure inorder to clear the lower surfaces of the flexures and of the rotaryprocessing table 238 to which they are attached. Since post 512 ispositioned so closely to the bottom of the flexures whenever a filter isinserted into a flexure, it is necessary in this embodiment to providesome up-and-down motion of post 512 while motor 510 moves to prevent thepost from damaging the table or the other flexures.

The post is fixed to post support 514. Post support 514, in turn isfixed to post mount 516 with a conventional screw fastener and two dowelpins. Post mount 516, in turn, is fixed to insulator block 518 byconventional screw fasteners and dowel pins. Insulator block 518, inturn is fixed to the output side of a precision linear stage 520. Linearstage or actuator 520 generally includes an integral pneumatic actuator(not shown) that is operated by a supply of compressed air selectivelyapplied to hose fittings 522. The two hose fittings permit the outputside of actuator 520 to be moved up or down (i.e. in the “Z” direction)with respect to the input side of actuator 520 by selectively applyingair under pressure by computer control to one or the other of fittings522.

The fixed side of actuator 520 is fixed to post base 526, which in turnis fixed to plate 502. As explained above, plate 502 is fixed to move inthe “X” direction with linear motor 510. Thus, both the flexure actuatorand post 512 translate together with linear motor 510. Flexure actuator264 can be moved in and out (toward or away) from the flexure 250 in the“Y” direction and post 512 can be moved up or down (toward or away) fromgap 282 of the flexure in the “Z” direction.

As mentioned, the head 124 is used to precisely place a single opticalfilter 196 into the gap 282 of each flexure 250, as illustrated by FIG.9A. In general, the flexure actuator assembly 264 is moved relative tothe rotary processing table 238 (FIG. 12) by linear actuator 510 to lineup the rollers 274 of the flexure actuator assembly 264 with anotherflexure 250 that is not yet provided with an optical filter 196 (asdepicted in FIG. 10A).

In an initial position, both the actuator assembly 264 and the post 512are moved away from table 238 and flexures 250. In this position, boththe actuator assembly 264 and the post 512 will not mechanicallyinterfere with table 238 and flexures 250.

Linear motor 510 is then energized to move both of assembly 164 and post512 in the “X” direction until they are positioned adjacent to aparticular flexure 250.

At this point, the actuator assembly is moved forward in the “Y”direction to engage and spread the flexure arms. Post 512 is movedupward (in the “Z” direction) until post 512 is positioned just belowgap 282. The order in which these two steps occur is not critical.

The “X” and “Y” gantries are energized to move head 124 until probe 152(holding filter 196 by vacuum) is located directly above gap 282. Oncein position, the “Z” stage is energized to move probe 152 downwardtoward gap 282. As the “Z” stage is lowered, filter 196 will engage post512 and stop moving. Probe 152 will collapse slightly as described aboveregarding the operation and construction of head 124. The “Z” stage isthen stopped with the filter held firmly between post 512 and probe 152.Vacuum is applied to post 512. The vacuum applied to probe 152 isreleased and head 124 is lifted up and away from the filter.

Once the filter is held in place between the two flexure arms, theflexure actuator assembly is withdrawn away from the flexure causing theflexure arms to move together and grip the edges of the filter with thethree fingers extending from opposing sides of the arms.

The vacuum applied to post 512 is released and post 512 is lowered awayfrom the filter.

At this stage, a new filter has been inserted into an empty flexure andboth the post 512 and flexure actuator assembly 264 have been withdrawnaway from flexure 250 and table 238. Linear motor 510 can then beenergized to move the flexure actuator assembly and the post to anotherflexure in order to insert another filter at the new flexure.

The above-described procedure is repeated until all four flexures 250(each in a respective nest 236) located on one side of the processingtable 238 are provided with an optical filter 196 that is to be tested.

Once the filters 196 have been tested (a process to be described below)they are similarly removed from the flexures in the following manner.First, the linear motor 510 moves the flexure actuator assembly until itis adjacent to the flexure to be unloaded. At substantially the sametime, probe 152 is moved downward using the “Z” stage until it contactsand holds the filter in that flexure by application of a vacuum to theprobe tip. Once the probe has gripped the filter, the flexure actuatorassembly is advanced until it spreads the flexure arms apart. Oncespread, the filter is supported by the probe alone, which is then raisedby its associated “Z” stage

Attention is next directed to FIGS. 7, 12, 23, and 24 for discussing oneparticular aspect or feature of the present invention, referred to as a“compactness” feature. In this regard, the rotary processing table 238is one of several elements or components of a rotatable assembly 288which shall now be described. Rotatable assembly 288 includes a rotarystage frame 600 that is fixed to base 103 and supports rotatable shaft602 on bearings 604. A rotary adapter 606 is fixed to the bottom offrame 600. Adapter 606 is also fixed to rotary actuator 608. An actuatorshaft 610 extends from actuator 608 and is rotated by pneumaticactuators 612 and 614. The linear motion provided by these pneumaticcylinders is converted to rotary position by an internal geararrangement (not shown). A preferred rotary actuator is model numberRLS-I-32×180°-NB-U4 manufactured by PHD. This actuator rotates a nominal180 degrees both in a clockwise and in a counter-clockwise direction.Air is supplied to actuator 608 by pneumatic tubing 616 coupled to thepneumatic ports of the actuator. One skilled in the art understands thatthe rotary processing table 238 may be made to rotate through its 180°span of motion under the control of a servomotor (not shown), ratherthan via pneumatic control.

A flexible coupling 618 is attached to both the rotary actuator shaft610 and to rotary shaft 602 to permit slight misalignment of the tworotatable shafts. Shaft 602 extends upward through frame 600 andterminates in a mounting flange 622. This flange is fixed to table 238using standard threaded fasteners.

When air under pressure is supplied to one port of actuator 608, itrotates clockwise approximately 180 degrees. Since the actuator isrotationally coupled to table 238, table 238 also rotates clockwiseabout 180 degrees.

When air under pressure is applied to the other port of actuator 608,the actuator rotates counter-clockwise approximately 180 degrees. Sincethe actuator is rotationally coupled to table 238, table 238 alsorotates counter-clockwise about 180 degrees.

The actuator assembly needs to rotationally position the table to withina few thousandths of an inch to insure that the filters are accuratelypositioned with respect to the goniometers in the goniometer station.Since the actuator selected for use cannot rotate to that degree ofaccuracy, additional components have been incorporated into the actuatorassembly to provide this precise positioning.

Frame 600 includes a cylindrical portion 624 in which the bearings 604and shaft 602 are mounted. In addition, it includes a stop block 626fixed to cylindrical portion 624 by conventional threaded fasteners.Stop block 626 does not rotate with table 238 and shaft 602, but isfixed with respect to base 103.

Adjustable rotation stops 628 and 630 are threadedly engaged with stopblock 626. These stops serve to limit the rotation of table 238 byengaging mating surfaces on stop block 640 that is fixed to the bottomof table 238. When stop 628 abuts stop block 640, table 238 stopsrotating in one direction. When stop 630 abuts stop block 640, table 238stops rotating in the other direction.

Rotatable assembly 288 also includes a first sensor 636 that generates asignal when stop 628 abuts stop block 640 and a second sensor 638 thatgenerates a signal whenever stop 630 abuts block 640. Sensors 636 and638 are actuated whenever sensor flags 632 and 634 interrupt a lightbeam passing between the opposing arms of the sensors.

Sensor flags 632 and 634 are fixed to stop block 640, which in turn isfixed to the underside of table 238. FIG. 25 is a partialcross-sectional view of block 640 showing the configuration of flag 634and its relationship with sensor 638. Flag 632 is arranged identicallyin block 640 but extends in the opposite direction to engage sensor 636.

Each of flags 632 and 634 fit into corresponding and adjacent slots 642formed in the bottom of stop block 640. Each of flags 632 and 634 haselongated slots 646 through which flag mounting fasteners 650 extend.The ends of fasteners 650 are threaded into stop block 640 such thatthey bind with flags 632 and 634, and fix them to stop block 640. Byloosening the fasteners, flags 632 and 634 can be slid back and forthinside their corresponding slots 642.

Each of flags 632 and 634 has a threaded adjusting screw 652 thatpermits the accurate and incremental positioning of each stop withrespect to stop block 640. The threaded ends of fasteners 652 abut stopblock 640.

The position of either of the stops is adjusted by rotating its fastener652 once fasteners 650 holding that flag to block 640 are loosened. Asfastener 652 is rotated, it moves its flag in its slot 642. Once theflag is in its the proper position, its fasteners 650 are tightened tolock it in that position.

In this manner, the position of the sensor flags can be adjusted, andtherefore the signal sent by the sensors to the computer indicating thatthe table is in the proper rotational position can also be adjusted. Byproviding these sensors and their associated flags, their signals areprovided to the computer which thereby knows when the table (1) is in afirst rotational position in which a first set of four flexures isdisposed for loading and unloading and a second set is disposed fortesting, or (2) is in a second rotational position in which the firstset of flexures is disposed for testing and the second set is disposedfor loading and unloading, and (3) is in a range of third rotationalpositions between the first two rotational positions in which notesting, loading or unloading should be done.

Attention is next directed to FIGS. 14-18, to discuss the goniometerstation 300 mentioned above. Preferably, two-axis goniometers are used;and a particularly preferred goniometer measures less than two inches(five centimeters) wide, less than seven inches (about eighteencentimeters) long, and less than four inches (ten centimeters) high. Forcompactness purposes, goniometers taking up less volume would be evenmore preferred. The illustrated goniometers can be placed on two-inch(five-centimeter) centers with no interference, within the total travelenvelope of each axis, between adjacent goniometers. The lower axisprovides ±6° of travel, while the upper axis provides ±5°. Theresolution of the upper axis is approximately 0.0007° while that of thelower axis is approximately 0.0005°. Actual accuracy for both axes isabout ±0.0035°. Both axes are controlled by a commercially-availableclosed-loop servo system using brushless DC (direct current) servomotorsand linear encoders. For each axis, commercially-available solid-stateoptical limit switches are employed to signal the end of travel/homepositions.

As will become apparent, the total number and spacing of adjacent nests236 on process table 238 is, in general, determined by the total numberand volume occupied by the goniometers incorporated into the apparatusof the invention. As was mentioned above, after all four filter nests236 are individually provided with a single optical filter 196, theprocess stage 238 is rotated a full 180° (FIGS. 3 and 12) for opticalfilter-testing purposes, to cause each such nest 236 to be preciselypositioned between a goniometer 302 and an associated optical detector304, as is illustrated in FIG. 14.

Referring to FIGS. 15-17, each goniometer 302 includes a pair ofspaced-apart apertured base plates 306 between which a channeled guidemember 308 is both sandwiched and fixedly mounted in a conventionalmanner. In particular, conventional threaded fasteners 310 (FIG. 15) areused to releasably fix the base plates 306 and the guide member 308together. The guide member 308 defines a generally elongated channel 312as well as a generally-cylindrical longitudinally disposed through bore314 communicating with the channel 312, as is shown in FIGS. 16 and 17.A conventional elongated worm-gear shaft 316 is rotatably mounted viaconventional spherical bearings 318A and 318B (FIG. 16) in the generallycylindrical through bore 314 in a conventional manner.

In particular, the outer bearing 318B, rotatably carrying one endportion of the worm-gear shaft 316, is removably retained within thegenerally-cylindrical through bore 314 via a conventional spanner nut320 (FIG. 16) which is removably threadedly joined to the channeledguide member 308 via intermeshing threads (not shown) in a conventionalmanner. The inner bearing 318A, rotatably carrying the opposite endportion of the worm gear shaft 316, is removably urged via an endportion of the worm-gear shaft 316 (as is illustrated) into abuttingengagement with an annular shoulder that is defined by the channeledguide member 308, which annular shoulder is concentric with thegenerally-cylindrical bore 314, as is shown in FIG. 16. The outer end ofthe worm gear shaft 316 (at bearing 318B) is non-rotatably (yetremovably) fixed to a flexible coupling 322 that is driven by acommercially available lower axis DC motor 324. The lower-axis DC motor324, which is provided power via a conduit 326, is mounted on thechanneled guide member 308 via an axially channeled motor mount 328. Inparticular, the lower axis DC motor 324 is releasably mounted on themotor mount 328 in a conventional manner using threaded fasteners 330(FIGS. 15 and 16). The motor mount 328 is removably affixed to thechanneled guide member 308 via threaded fasteners (not shown) in asimilarly conventional manner. The lower-axis DC motor 324 includes arotatable motor shaft 332 (FIG. 16) on which the flexible coupling 322is non-rotatably (yet removably) mounted. In this regard, the axiallydisposed channeling of the motor mount 328 is so dimensioned relative tothe external surfaces of the flexible coupling 322 such that theflexible coupling 322 is able to rotate relative to the motor mount 328with no interference between the flexible coupling 322 and the motormount 328.

A “tip” feature of the illustrated goniometer 302 shall now bediscussed. A worm gear-driven platform 334, having a lower end portiondisposed into the elongated channel 312 of the guide member 308, definesa threaded bottom portion that intermeshes with the worm-gear threads onshaft 316, as shown in FIG. 16. A grooved guide member 336 (FIG. 17A),spaced above the channeled guide member 308 (FIGS. 16 and 17), ismounted on top of the driven platform 334 (FIG. 16).

Spaced-apart lower portions of the grooved guide member 336 define anarcuate groove 344, one of which is shown in FIG. 17A; andinwardly-disposed upper surface portions of apertured base plates 306respectively define grooves 346 of complementary arcuate curvature intowhich conventional spherical bearings 348 (FIGS. 17 and 17A) aredisposed. Spaced-apart optical limit switches 350, operably connected tothe lower-axis DC motor 324, are fixedly mounted in an upper surface ofthe channeled guide member 308 (FIGS. 15-17); and an opticallimit-switch flag 352 (FIG. 17) which is fixedly carried by the groovedguide member 336, and which is adapted for engagement with one of thelimit switches 350 in a conventional manner, is operably disposedtherebetween.

In operation, activation of the lower axis DC motor 324 powers andcauses rotation of the worm-gear shaft 316 which, in turn, causesmovement of the worm gear-driven platform 334 to the left or right, asshown in FIG. 16. While such motion of the worm gear-driven platform 334is linear relative to the channeled guide member 308, the resultantrelative motion between the grooved guide member 336 and the channeledguide member 308 is arcuate, because movement of the grooved guidemember 336 is tied to the worm gear-driven platform 334 via the dowelpin 342 (FIG. 17) and is guided by the arcuate grooves 344 and 346 (FIG.17A) and ball bearings 348 therein.

A “tilt” feature of the illustrated goniometer 302 shall now bediscussed. An underside surface of the grooved guide member 336 definesa generally rectangular channel 354 (FIG. 17A) into which the drivenplatform 334 is disposed (FIG. 17); and an intermediate portion of thegrooved guide member 336 defines a generally cylindrical through bore356 (FIG. 17A) into which a spur-gear shaft 358 (FIGS. 16 and 17) islongitudinally disposed. The spur-gear shaft 358 is rotatably mounted inspaced-apart bearings 359 (FIG. 16) longitudinally mounted within thecylindrical through bore 356 of the grooved guide member 336.

An upper axis DC motor 360, provided electrical power in a conventionalmanner via a conduit 362, is removably operably connected in aconventional manner to a gearbox 364 having an output shaft 366 operablyconnected to spur-gear shaft 358 via a flexible coupling 368. A hollowmotor mount 370 (FIG. 16), within which flexible coupling 368 is freelyrotatable, is removably affixed to grooved guide member 336 via threadedfasteners (not shown), and has gearbox 364 removably mounted thereon(FIG. 16) in a conventional manner via threaded fasteners 372.

An upper surface of grooved guide member 336 defines an elongated slot374 (FIG. 17A); and a spur gear-driven platform 376 (FIGS. 16 and 17),longitudinally disposed in the slot 374 (FIG. 17) has a lower portionwhich defines threads that intermesh with the threads of the spur-gearshaft 358. Mounted on the spur gear-driven platform 376 is a groovedtilt-axis mount 378 (FIGS. 16 and 17).

Spaced-apart tilt-axis side plates 386 have the tilt-axis mount 378removably affixed therebetween (FIGS. 15 and 16) via conventionalthreaded fasteners 388. Spaced-apart upper portions of the grooved guidemember 336 define an arcuate groove 390, one of which is shown in FIG.17A; and inwardly-disposed lower surface portions of the tilt-axis sideplates 386 respectively define grooves 392 of complementary arcuatecurvature into which conventional spherical bearings 394 (FIGS. 17 and17A) are disposed. Spaced-apart optical limit switches 396, operablyconnected to the upper-axis DC motor 360, are fixedly mounted in anupper surface of the grooved guide member 336 (FIG. 16); and a pair oflimit-switch flags 398 which are fixedly carried by the groovedtilt-axis mount 378, and which are adapted for engagement withcorresponding ones of the limit switches 396 are operably disposedtherebetween.

In operation, activation of the upper-axis DC motor 360 powers andcauses rotation of spur-gear shaft 358 which, in turn, causes movementof the spur gear-driven platform 376, generally to the left or right(FIG. 17) along an arcuate path that is defined by the interactionbetween balls 394 as they roll in grooves 390 and 392. These balls andgrooves together constrain the tilt-axis to rotate about an axis locatedat the top of the goniometer.

In particular, balls 394 and grooves 390 and 392 in which they roll havebeen configured to rotate the tilt_axis portion of the goniometer(including collimator 500) about an axis that is in the plane of thelower surface of a filter loaded into the flexure immediately above thegoniometer. As a result, when motor 360 rotates, the tilt-axis pivotsabout an axis that is parallel to the “Y” vector that defines the “Y”direction.

Whenever the lower motor 324 is engaged, it rotates the worm gear shaft,which engages platform 334. As in the example of motor 360, above, thiscauses the platform 334 and all the components mounted on it, includingguide member 336, motor 360 and collimator 500 mounted on member 336 tosimilarly rotate. In the case of motor 324, however, this rotation isconstrained by balls 348 that travel in grooves 346 and 344. Since thisball and groove arrangement is orthogonal to the ball 394 and groove 392arrangement located on the upper portion of the goniometer, the motioncaused by motor 324 is orthogonal to that of motor 360.

As in the case of motor 360, above, balls 348 and grooves 344 and 346 inwhich they roll are configured to rotate the platform 334, the groovedguide member 336 and all components mounted on it (including collimator500) about an axis that is in the plane of the lower surface of a filterloaded into the flexure immediately above the goniometer. As a result,when motor 324 rotates, these components pivot about an axis that isparallel to the “X” vector that defines the “X” direction. This vectoris orthogonal to the “Y” vector.

Summarizing, when motors 360 and 324 rotate to drive the goniometer, theupper portions of the goniometer pivots about two orthogonal pivotalaxes that are in the plane of the lower surface of a filter mounted inthe flexure immediately above that goniometer.

In this manner, the goniometer can be tilted to provide a specificangular orientation of the collimator with respect to a planar surfaceof the filter, while at the same time keeping the collimator pointed atthe surface of the filter. As we will discuss below, each goniometer isprovided with translating “X” and “Y” stages that move the goniometer inthe “X”-“Y” plane while not changing the angular orientation of thegoniometer with respect to a surface of its corresponding filter.

In this manner, the light beam transmitted by the collimator through thefilter can be separately and independently adjusted both (1) angularly(i.e. without changing the point of incidence of the light on thesurface of the filter), and (2) translationally across the surface ofthe filter (without changing the angular orientation of the incidentlight beam with respect to the filter).

It will therefore be appreciated by those skilled in the art, becausethe plural goniometers 302 are operably disposed upwardly towardassociated optical detectors 304 (FIG. 14), that the two-axis “tilt” and“tip” features, which are thus provided by the lower-axis and upper-axisDC motors 324 and 360 (FIG. 15), will enable the operative end of eachgoniometer 302 to “track” along an arcuate path in the “X” plane as wellas along an arcuate path in the “Y” plane, simultaneously, where thecenter of each such arcuate path is spaced above the goniometer 302,which is a result of the grooves 344 and 346 in the guide member 336 andthe spaced-apart lower side plates 306 as well as the grooves 390 and392 in the guide member 336 and the spaced-apart upper side plates 386,as shown in FIG. 17A.

A scale mount 400 (FIGS. 15 and 16) is fixed to the tilt-axis sideplates 386 via threaded fasteners 402 for mounting an optional opticalscale (not shown). An upper axis (tilt) encoder 404 (FIGS. 15 and 16)for optically detecting the optical scale in order to determine thedegree of tilt of the upper stage, is fixedly-mounted in a conventionalmanner to an upper encoder bracket 406 (FIG. 16) which, in turn, ismounted in a conventional manner on the grooved guide member 336. Anencoder cable 408 (FIG. 15), is operably connected to the upper axis(tilt) encoder 404. A lower axis (tip) encoder 410 (FIG. 17), disposedbetween the lower axis base plates 306, is for detecting the degree oftip.

Referring to FIG. 18, each goniometer 302 (FIG. 14) is mounted on aseparate X-Y translation stage 412, which allows each goniometer 302 totranslate in both the “X” and “Y” directions in a plane that ishorizontal to the base 103.

Each goniometer 302 includes an associated collimator 500 (FIGS. 14-17)having a base 502 (FIG. 15) that is fixed to the tilt-axis mount 378 viaconventional fasteners 504. For each goniometer 302, the associatedcollimator 500 is disposed generally upwardly, toward a correspondingnest 236 on the rotary processing table 238, as is shown in FIG. 14.Also, for each goniometer 302 there is an optical detector 304 which isoptically facing its associated goniometer 302 and spaced sufficientlyvertically above its associated collimator 500 as to permit theprocessing table 238 to rotate therebetween (in the manner describedabove), to present a single optical filter 196, which is held in asingle associated nest 236 of the processing table 238 by the forwardportion 280 of the associated flexure 250 (FIG. 10B), for optical filtertesting. The associated optical detectors 304, disposed above the rotaryprocessing table 238 and optically facing each respective one of thefilter nests 236, are affixed with fasteners 505 in a conventionalmanner to a transverse frame 506 (FIG. 14) supported by the base 103.

For each goniometer 302, the associated lower-axis DC motor 324 as wellas the associated upper-axis DC motor 360 are together operated to causethe goniometer 302 to “tilt” and/or “tip” (as described above) so thatthe associated collimator 500 may be directed precisely at the singlecorresponding optical filter 196 that is to be tested.

In general, laser light from a conventional tunable laser source coupledto each collimator 500 is directed toward the lower surface of a filter196. This laser light is reflected off the lower surface of filter 196if the wavelength of the light is a non-accepted wavelength. If thelight is at an accepted wavelength, it is transmitted through the filterand impinges upon associated optical detector 304. Detector 304 convertsthat incident light energy into an electrical signal, which is fed tothe system.

Light at wavelengths that are not accepted (i.e. reflected) by filter196 is reflected by the optical filter 196 and passes back through thecollimator 500 into light circulator 616 and into power module 604_([PC1]).

More particularly, in a first test step, goniometer tip and tilt areadjusted until the energy of the reflected light at a wavelength outsidethe accepted (i.e. transmitted) wavelengths of the filter is a maximumas measured by the power module 604.

Inherently, light energy reflected back into the collimator 500 is at amaximum when the laser beam is oriented precisely 90° relative to thesurface of each optical filter 196 (i.e., precisely “normal” to thelower surface of the filter). In this regard, for each goniometer 302,the associated lower-axis and upper-axis DC motors 324 and 360 areoperated to cause the light from the associated collimator 500 to beprecisely normal to the surface of a single optical filter 196 that isto be tested. This requires that the goniometer 302 be able to adjustits tip and tilt by very small increments of preferably 0.007° or less.

To do this, a computer moves motor 324 in a sequence of steps, readingthe intensity of the reflected light signal. After the desired alignmentmaximizing reflected light energy is achieved, the wavelength of lightdirected onto each of the filters 196 is varied in small incrementswithin a range of wavelengths dependent on the type of filters beingtested, since each filter 196 must transmit a preselected wavelengthrange of light as dictated by its performance specification. Filtersthat do not transmit the correct wavelength are rejected or classifiedaccording to their transmission characteristics.

Reference is next directed to FIG. 19 wherein a mainframe 600 includes aconventional tunable laser 602, a power sensor module 604 and aninterface module 606, all of which are commercially available. The laser602 is a conventional tunable laser optically coupled via a conventionalfiber-optic cable 608 in a known manner to a commercially-availableone-to-four (1:4) beam splitter 610, which optically splits the laserbeam from fiber-optic cable 608 into four output beams, each of which iscarried by a separate conventional fiber-optic cable 612 to an opticalfilter-testing station 614. Each such optical filter-testing station 614includes a commercially-available reflected-light circulator 616, andone each of the collimators 500, optical filters 196 and opticaldetectors 304, as described above. An electrical connector 618electrically connects in a conventional manner the optical detector 304to the interface module 606 and an optical connector 620 opticallyconnects via a conventional fiber optic cable the power sensor module604 to each reflected-light circulator 616.

In operation, laser light from the laser source 602 in the mainframe 600is passed via the fiber-optic cable 608 through the laser-beam splitter610, which optically splits such laser light into plural (preferablyfour) laser-based light beams. Each such split light beam is passed viathe fiber-optic cable 612 to an associated reflected-light circulator616. From the reflected-light circulator 616, the laser beam is passedthrough the associated collimator 500 and is incident upon an associatedoptical filter 196 as above described. Reflected light from the opticalfilter 196 that passes back through the associated collimator 500 isreceived by the associated reflected-light circulator 616 and isthereafter passed via the optical connector 620 to the power sensormodule 604 where its intensity is measured. The position of thecollimator 500 is adjusted using motors 324 and 360 to tip and tilt thegoniometer until maximum intensity of the reflected light is achieved.After alignment, the transmitted light received by the associatedoptical detector 304 is passed from the optical detector 304 via theelectrical connector 618 to the interface module 606. The wavelength ofthe tunable laser scans a range of 1 to 30 nanometers in smallincrements, preferably ranging in incremental size between 1 and 10picometers, both above and below the specified wavelength of the opticalfilter under test to measure its transmission characteristics.

Reference is next directed to FIG. 20, which is a schematic showing thepath of transmitted and reflected light. In FIG. 20, transmitted lightfrom laser 602, shown as a solid line, passes through the circulator 616and its associated collimator 500 and through an individual opticalfilter 196. Transmitted light from such optical filter 196 is receivedby the associated optical detector 304. An electrical signal,represented by the dot-and-dashed line, is passed to the interfacemodule 606 (FIG. 19).

The optical detector 304 is spaced above its associated optical filter196 by the distance Z_(T), which indicates vertical transmitted-lightspacing. A reflected wavefront, represented by the dashed line, isreflected by the optical filter 196 (in response to the incidenttransmitted light passed from collimator 500 to optical filter 196) backthrough the associated collimator 500 and reflected-light circulator616. The light circulator 616 passes the reflected light (as shown bythe dashed line) back to the power sensor module 604 (FIG. 19) via theoptical connector 620. The filter 196 is spaced above its associatedcollimator 500 by the distance Z_(R), which indicates verticalreflected-light spacing.

Referring back to FIG. 17, a filter aperture mask 2302 is disposed abovefilter nest 236 in the path of transmitted light to mask off stray lightthat passes through filter 196 before that stray light arrives atdetector 304. The mask has a small circular opening or aperture 2304through which the laser light passes to reach detector 304.

FIG. 23 shows the aperture mask in greater detail in perspective view.FIG. 22 shows the aperture mask in cross section in its position over afilter nest 236 during filter loading and unloading. FIG. 22 shows theaperture mask in side view, extending across all four filter nests 236on one side of table 238. For clarity of illustration, this mask is notshown in the other FIGURES of this application. Nonetheless, all theembodiments of this invention preferably employ this mask to increasethe performance of the system by masking off stray environmental lightand light scattered from the surface of the filter during testing at thegoniometer test stations.

As shown in FIG. 23, the mask is in the form of an elongate bar 2306that defines several apertures. Table 238 has two such masks 2302. Onemask 2302 is disposed across four flexures on one side of the table andthe other is disposed across four flexures on the opposite side of thetable.

Each of the four flexure locations along the mask defines a plurality ofapertures, including (1) a large aperture 2308 sized to pass the tip ofprobe 152 when it is lowered to the flexure during insertion or removalof filter 196 from the flexure, (2) a small aperture 2304 that is sizedto permit the passage of laser light to detector 304 in the goniometertesting position, and (3) an elongate aperture 2310 sized to permit thepassage of the beam of laser light for tests conducted with thegoniometer disposed at an acute angle with respect to the bottom surfaceof the filter. According to another embodiment of the aperture mask2302, the mask may define but a single sized/shaped aperture, such asdefining only elongated apertures 2310. This aperture is utilized duringall forms of testing. Thus, the aperture mask 2302 does not need to beadjested from test to test, yet still serves its basic function ofreducing the transmission of stray light.

The bar also includes two couplings 2312, here shown as two tabs locatedat and extending outward from either end of bar 2306. These couplingsare configured to be coupled to a mating coupling (not shown) that isfixed to plate 502, which is driven side-to-side in the “X” direction bylinear motor 510.

The mask is fixed to table 238 by two headed fasteners 2314 disposed ateach end of the mask. These fasteners are disposed in slots 2316 definedby the mask that are located at either end of bar 2306. As shown in FIG.12, the two fasteners 2314 are fixed to and extend upward from table 238at either end of the table.

Slots 2316 receive the fasteners and are sized to permit the fastenersto slide in the slots, or rather, since the fasteners are fixed to thetable, to permit the aperture mask to slide side-to-side with respect tothe table.

The slots and fasteners are disposed and configured such that the maskcan be shifted by linear motor 510 to any one of three positions, yetwill hold the mask in each of these positions when table 238 is rotated180 degrees from the filter loading position to the filter testingposition.

A first position of mask 2302 with respect to table 238 is a loadingposition in which the lower tip portion of probe 152 can pass throughall four large apertures 2308 in order to place a filter 196 in each ofthe flexures during flexure loading and to remove each of the filtersduring flexure unloading. Thus, once linear motor 510 shifts mask 2302to the loading position, all four flexures can be sequentially loadedusing probe 152 with no necessary intermediate movement of mask 2302with respect to table 238.

A second position of mask 2302 with respect to table 238 is a testingposition in which the laser light beams generated by the fourcollimators 500 can simultaneously pass through all four small apertures2304 (the position shown in FIG. 17) and impinge upon the bottom surfaceof filters 196 at each of the four filter nests. By providing a positionof mask 2302 at which all the collimators can reach their filters withtheir orthogonal laser beams, all the filters can be simultaneously orsequentially tested without having to move mask 2302 between each filtertest.

A third position of mask 2302 with respect to table 238 is a secondtesting position in which the laser light beams generated by the fourcollimators 500 can simultaneously pass through all four elongateapertures 2310 and impinge upon the bottom surface of filters 196 ateach of the four filter nests. By providing a position of mask 2302 atwhich all the collimators can reach their filters, all the filters canbe simultaneously or sequentially tested without having to move mask2302 between each filter test.

In operation, the linear motor 510 will move laterally until theaperture mask coupling supported by linear motor 510 can engage itsmating coupling 2312 on mask 2302. Once engaged, linear motor 510 movesin the “X” direction to slide mask 2302 with respect to table 238.During this process, table 238 does not move, but is held stationary.

Once mask 2302 is moved to the proper location, thereby locating largeaperture 2308 at each of the flexures, the coupling on linear motor 510is disengaged from coupling 2312 on mask 2302. Filter loading andunloading can then begin.

Once a new set of filters-to-be-tested are loaded, however, and beforethe table 238 (and hence the filters 196) are rotated to locate thefilters at their goniometers for testing, the mask is shifted to locatethe elongate or small circular apertures in position above the flexures.Once in this position the table is rotated and testing begins.

Alternatively, the mask 2302 may be fixedly mounted so as to beinterposed between the optical filter under test and the opticaldetector 304. Per such an embodiment, the mask 2302 remains stationary,simplifying the testing system.

The mask, while useful, is not necessary to the operation of the otherparts of the system. Certainly there are many filters and substratesthat may be tested in an automatic fashion without an aperture mask. Inaddition, each flexure may be provided with an individual mask, althoughthese would require either more time or more actuators to move them.While the mask is operated when the flexures are at their loadingstations, a mask actuator could as easily be disposed in the region ofthe goniometer to move the mask once it is back by the goniometerstations. Alternatively, a fixed or movable mask could be mounted by thegoniometer stations that does not rotate with the table.

The following discussion summarizes operation of the optical filtertesting and sorting apparatus of the present invention. The apparatus,capable of operating continuously, will pause automatically in responseto optical filter availability (input) and take-away (output)constraints as well as for maintenance reasons.

The general overall flow of the filter testing process includes locatinga filter on either the tape from the tape frame 111 (or the gelpacks/vacuum release trays 702), moving them to and inserting them inthe flexures, rotating table 238 until the flexures are located betweenthe collimator and the detector at the four testing stations, testingthe filters, rotating the table back to its original position, removingthe four filters from the flexures, and inserting them in the outputtrays 112.

Due to the construction of the machine, there are several of theseoperations that can be overlapped in time. This overlapping permits themachine to be engaged in several testing operations simultaneously, thusincreasing productivity.

For example, loading and unloading can take place at the same time thefilters are being tested. Table 238 has eight flexure stations, four oneach side of the table, with one set of four in a testing position atthe goniometers while the other set of four flexures is facing outwardto be loaded or unloaded by the “X”, “Y” and “Z” stages. Thus, at thesame time the goniometers are performing their tip and tilt adjustmentsor their scanning of wavelengths, the “X”, “Y” and “Z” stages can removetested filters from the four flexures facing the “X”, “Y” and “Z” stages(i.e. the set of flexures that are not located at the goniometer teststations) and replace them with four new filters to be tested.

As another example of additional overlapping functions, the “X”, “Y” and“Z” stages can also perform various “housekeeping” functions whilewaiting for the goniometers to perform their testing. For example,assume the four filters that have been tested have already been removedfrom the flexures, placed in output trays, and have been replaced withfour additional to-be-tested filters in the four flexures that are notat the goniometer test station. At this point the “X”, “Y”, and “Z”stages may be operated to move trays of tested parts from one area oftable 114 to another area of table 114.

As yet another example, the “X”, “Y”, and “Z” stages can move effector120 to grasp and move trays of tested filters from the sorting area oftable 114 to the depot area (i.e. row 150).

As another example of these housekeeping functions, the “X”, “Y” and “Z”stages can pick to-be-tested filters off of the tape frame 111 and placethem in the vacuum trays 702. In addition, while testing is occurring athe goniometer stations, effector 120 can pick and place lids that arestacked in depot locations (row 150) or are on top of theircorresponding output trays 112 or gel pack trays 702.

As another example of the system's ability to perform multipleoperations simultaneously, the system's four goniometers can be operatedsubstantially simultaneously. For example, as one goniometer is adjustedto a proper tip and tilt angle using motors 324 and 360, the othergoniometers can be likewise simultaneously adjusted.

As another example, while one goniometer detector is receiving atransmitted light signal from the laser light source, the othergoniometer detectors can likewise simultaneously receive the same signalat their detectors.

All of these features are possible due to the arrangement of the systemdescribed herein.

Referring to the flow chart of FIG. 21, at step 2100, a tape frame 111or one or more gel pack trays 702 are loaded (FIG. 7) into the machine.

At step 2102, lot information representative of the optical filters 196to be tested (FIGS. 8A and 8B) is preferably either scanned from barcode information associated with the to-be-tested optical filters 196located on the tape frame 111 or the gel pack trays 702 by a bar codereader (not shown) or is manually entered by the operator into thesystem's computer.

This lot code information specifies a recipe number that preferablyincludes (1) the nominal filter-to-filter pitch (both in “X” and in “Y”)of the filters, (2) the nominal dimensions of the filters (thethickness, the width and the height of the filters), (3) the nominallocation of one filter (the reference filter) with respect to areference point on the tray itself, (4) the nominal center wavelength ofthe passband of the filters, and (5) the nominal passband width of thefilters.

At step 2104, machine vision camera 121 (FIGS. 7 and 8A) scans thetarget area for each such optical filter 196. The system moves camera1212 using the “X” and “Y” stages until the camera is located over thelocation of the reference filter.

At step 2106, the system takes a picture of the tray at this referencelocation using camera 121.

At step 2108, the system analyzes the image using the previously enterednominal dimensions of the filter to extract edge characteristicsindicative of a filter. If the image processing indicates that an entirefilter is within the image (step 2110), the system continues processingat step 2110.

If the system is unable to identify a filter in the image that matchesthe nominal dimensions of the filter, the system then moves to anotherlocation adjacent to the nominal location and repeats the image captureand image processing performed in steps 2106 and 2108.

In the preferred embodiment, the system is configured to move camera 121in a predetermined path in the vicinity of the reference filter, movingfrom one predetermined location to another predetermined location untila complete image of a filter is in the camera's (121) field of view.This search path may vary based upon the size of the filter (inparticular the width and height of the filter). For larger filters,larger increments of motion are preferably made. For smaller filters,smaller increments of motion may be made.

The preferred path along which the camera is moved in successiveattempts to get an image of an entire filter is preferably curvilinearsuch as a spiral path or a circular path. Starting from the nominallocation of the first filter, previously stored in the computer, thecamera is moved in an outward spiral. Alternatively it may be moved to asequence of locations that collectively define several substantiallyconcentric circles.

The system performs this moving, image gathering and image analyzingprocess at a succession of locations along the path until a filter isultimately found, at which point processing continues at step 2110.

In step 2110, the system calculates the location of the geometric centerof the filter based upon the actual location of the edges of the filterextracted from the image. The system also determines the rotationalangle of the filter in the “X” and “Y” planes and about the “Z” axis—the“theta” angle of the filter.

The “X” and “Y” locations of the center of the filter are determinedbased upon (1) the “X” and “Y” position of the camera (typically thecenter of the image shown in the camera) and the “X” and “Y” offset ofthe filter within the camera image. The combination of the “X” and “Y”camera location and the “X” and “Y” offset of the center of the filterwithin the camera image itself provides the actual “X” and “Y” locationof the filter.

In step 2110, the system also saves data indicative of the actual “X”and “Y” location of the center of this reference filter (the “actualreference location”) for later use when the system returns to the trayto locate and pick up subsequent filters in the tray.

In step 2112, the system moves the “X” and “Y” stages to position vacuumprobe 152 directly above the center of the reference filter. Asdescribed above, the camera 121 and the probe 152 are both supported onthe “X” and “Y” stages, and are fixed with respect to each other in the“X” and “Y” directions. As a result, they have a fixed “X” and “Y”offset from each other. This offset is electronically stored in thecomputer. and is used to offset the “X” and “Y” stages to position theprobe directly over the center of the filter.

At substantially the same time that the “X” and “Y” stages move theprobe 152 into position in step 2114, the system also moves the “X” and“Y” stages (on which the lift pin assembly in mounted) to position thelift pin directly underneath the actual center of the filter. While thepositioning of probe 152 and the lift pin assembly may be donesequentially, it is preferably that they move simultaneously in order toreduce the overall cycle time of the system. Since one feature of thepreferred embodiment of this invention is to locate the pin and theprobe on separate “X” and “Y” translatable stages, the present system iscapable of simultaneous positioning of both the probe and the pin.

Once the center of the probe reaches the center of the filter inquestion, it is lowered until it just contacts the filter in step 2116.In the preferred embodiment, the system also applies a vacuum to probe152 to adhere the filter to the bottom of the probe.

In step 2118, the system raises the lift pin, now in position under thefilter, by applying compressed air to cylinder 206 until the filter islifted a predetermined distance. The system monitors the signal fromsensor 228 to determine when the lift pin has been raised to the properheight. As described above, this driving upward of the filter againstprobe 152 is accompanied by the step of peeling a portion of the tapeaway from the filter, thus leaving the filter stuck to a small portionof the tape.

As a reminder, not every filter to be tested is held on the adhesivetape on tape frame 111. Some filters to be tested are located in gelpacks 702 on vacuum mounts 700. In the case where filters are held ingel packs, the process is slightly different. When gel packs are used,the lift pin assembly is not used to help release the filters, and thusthe steps above related to moving and positioning the lift pin assemblyare not performed. Indeed, the entire lift pin process may be eliminatedif the adhesive to which the filters are held is of a sufficiently lowtackiness that it will release the filters by the vacuum applied toprobe 152 alone. New adhesives and packaging methods for filters will nodoubt be developed that may permit the elimination of the lift pinassembly.

Gel packs are formed of a plastic tray over which a thin flexible matrixis attached. The matrix is formed of a tacky gel material. The filtersare stuck to this matrix. Between the matrix and the inside bottom ofthe tray is an irregular grid. This grid may be in the form of a wovenmat. A vacuum is applied to the bottom side of the gel pack, shown inFIG. 2A, causing the matrix to be pulled downward and into close contactwith this irregular grid. This happens because the vacuum pulls air outfrom between the irregular surface and the planar matrix. The irregulargrid does not flatten out, however. The gel matrix assumes an irregularbumpy surface to match the irregular grid.

When the matrix is distorted downwardly, portions of the matrix arepulled away from the bottom surface of each of the filters stuck to thetop surface of the matrix. The bottom surfaces of the filters generallycontact an equal area of adhesive coated matrix before the vacuum isapplied. When the vacuum is applied and the matrix deforms downwardlycurving and conforming to the grid, at least a portion of theadhesive-coated matrix pulls away from the back of the filters. Thispulling away causes all of the filters in the gel pack to be in contactwith a smaller area of sticky gel, and thus to be held more weakly tothe matrix than they are when no vacuum is applied and the matrix is inits normally flat planar orientation.

As a result, when the system applies a vacuum to the gel pack using thearrangement shown in FIG. 2A, the system provides a reduction in surfacecontact area that is similar to the reduction in adhesive bond areaprovided by operation of the lift pin, but without the lift pin assemblyapparatus, and merely by the application of a vacuum to the gel pack.

All that is required is a tray mount that is configured to receive thegel pack and the application of a vacuum to the underside of a gel pack.This capability is provided by mounts 700 illustrated in cross-sectionin FIG. 2A, shown in FIGS. 1 and 2, and discussed above.

Referring back to the process, in step 2120, the system lifts probe 152by commanding the “Z” stage to raise, thereby pulling (by the vacuumapplied to probe 152) the filter away from the remaining portion of thetape to which the filter is adhered. Alternatively, the probe retractsfrom the gel pack and similarly pulls the filter away from the gelmatrix.

If the probe 152 is retrieving filters from a gel pack, the step ofapplying a vacuum to the gel pack is performed just before step 2118 inorder to reduce the surface contact between the filter and the gel pack.This insures that the probe is capable of pulling the filter free fromthe gel pack in step 2118. Applying vacuum after step 2106 also assuresa higher quality image of the filter when the image of the filter isacquired.

Once removed from the tape, the “X” and “Y” stages translate the filteron the end of the probe to the flexures in step 2122. Each flexure has apredetermined X-Y location stored in the computer, expressed either asan absolute location or as an offset from a predetermined referencelocation, that is accessed by the system's computer to provide the X-Ylocation of each flexure to the system.

During the process of translating the filter, the system also commandsthe “theta” stage to rotate the filter to a proper graspable position.In the preferred embodiment, this position is one that will permit thethree protrusions 283, 284, 286 on the arms of flexure 250 toeffectively grasp the filter when the system retracts the flexureactuator assembly and thereby releases the flexure arms 262.

In the preferred embodiment, the system determines the rotational angleof the filter based upon the electronic image received from camera 121,as described above in step 2106. This angle indicates the rotationalposition of the filter in its tray, and with respect to the “X” and “Y”axes of the system.

The system retrieves the “theta” or rotational angle of the filter aboutthe “Z” axis. This value was calculated during step 2110 above in whichthe filter was identified and its center calculated.

The system then converts the theta angle into a drive signal that isapplied to the theta stage. In response to this signal, the theta stagerotates through an angle that is calculated to align the filter with itsintended flexure. Once the proper filter angle has been achieved, thetheta stage stops rotating.

This rotation can occur at any time between the time the filter has beenpicked up by probe 152 at step 2120 and the time that the flexure armsare released to grasp that same filter. In the preferred embodiment,this theta rotation is effected as the filter is translated by the “X”and “Y” stages to the desired flexure.

Before the filter that the “X” and “Y” stages are moving to a flexurecan be inserted into that flexure, table 238 must first be prepared bymoving the aperture mask into the proper position. This occurs in step2124.

To permit loading, the aperture mask must be shifted to located thelarge apertures just above gap 282 in which the filters are inserted.The system translates the linear motor 510 until its coupling engagescoupling 2312 on the aperture mask. Once engaged, linear motor 510 movesin a direction and for a distance that aligns all four of the largeapertures underneath each of their corresponding flexures.

Since a single manipulation of the aperture mask moves all four largeapertures simultaneously into position at their flexures, this step onlyoccurs once during flexure loading.

In step 2126, the flexure actuator assembly and the post assembly aremoved into lateral position at the flexure that will receive the filtersuspended from probe 152. Linear motor 510 moves plate 502 until theflexure actuator assembly, is located directly in front of and betweenthe two arms of the flexure. In this position, post 512 is also locateddirectly below the flexure.

In step 2128, the system prepares the flexure to receive the filter. Aspart of this preparation, the system drives post 512 upward by applyingcompressed air to stage 520. Stage 520 moves post 512 upward until thetop surface of post 512 is substantially coplanar with the bottom planarsurface of flexure 250. After the post is positioned, in step 2130 thesystem drives flexure actuator 294 forward by applying compressed air topneumatic stage 266. This forward motion of stage 266 separates theflexure arms.

The system then inserts filter 196 into the flexure. In step 2132, thesystem commands the “Z” stage to lower probe 152 a predetermined amountthat will locate filter 196 between the arms of the flexure and place itin contact with the top of post 512.

In the preferred embodiment, the system drives the “Z” stage downward toa position at which probe 152 is slightly compressed in its sleeve, theguaranteeing that the filter will be mechanically held between and incontact with both the post and the probe by their contact with opposingplanar sides of the filter.

The system then applies a vacuum to post 512 to hold the filter in step2134. Once the vacuum has been applied to the post and the systemdetermines (using a vacuum sensor) that the vacuum has been applied, thesystem removes the vacuum from the probe. The system then determines(based upon a vacuum sensor disposed to sense the probe vacuum) that thevacuum has been removed and drives the “Z” stage (and therefore probe152) upward away from the filter nest to permit completion of flexureloading (in step 2138).

The system then retracts the flexure actuator assembly in step 2136,thereby releasing the flexure arms, and permitting the flexure arms tomove inwardly and mechanically engage the filter. The system thenreleases the vacuum applied to post 512, and drives stage 520 downwardto lower post 512 away from the filter.

Once a single flexure has been loaded, the system repeats the process ofsteps 2104-2138 three more times as indicated by step 2140 (with theexception of the step of shifting the aperture, which is not repeated ateach successive filter placement) until all four apertures are loaded.

At the conclusion of this loading process, the system moves aperturemask 2302 in step 2142 using the process described above in conjunctionwith step 2124. The system commands linear motor 510 to move theaperture mask to either of its two testing positions, depending upon theparticular tests that the system will perform on the filters.

Once four untested filters are mounted in their corresponding flexuresand the system has completed its optical testing of four filterspreviously loaded into the machine and located at the test stations, thetested filters are moved away from the test stations and the fourjust-loaded filters are moved into position at the test stations. Thishappens in step 2144.

The system then rotates table 238 by applying compressed air to one ofthe two opposed cylinders 612. This causes shaft 602, and hence table238 to begin rotating. The system applies air to the appropriatecylinder 612 until stop block 640 on the bottom of table 238 abuts oneof adjustable stops 628.

At substantially the same time this abutting occurs, one of opticallimit switch flags 632 or 634 (depending upon which of the two opposed180 degree positions the table is being driven to) causes itscorresponding sensor 636 or 638 (again, depending upon the position thetable is driven to) to generate a signal indicating that the table hasrotated 180 degrees. The air pressure the cylinder holds the table inposition against adjustable stop 628 or 630 (again, depending upon therotational position of the table). Note that this process is reversedusing the other one of cylinder 612 and the other one of the two limitswitches and flags when the table is moved back to its original positionafter testing.

Once the table 238 has been rotated in step 2144, as indicated by sensor636 or 638, the four to-be-tested filters are now at their correspondinggoniometer test stations and the system begins optical testing. Notealso that, at the same time the table rotated four filters into positionfor testing, it simultaneously moved the four filters on the oppositeside of the table into position for unloading and sorting by probe 152.

At step 2146, the system optically aligns each goniometer 302 with acorresponding nest 236 (FIGS. 12 and 14) by selectively driving motors324 and 360.

At step 2148, the system controls goniometer 302 and performs a signalmaximization routine to determine signal as a function of angularposition. The system positions each goniometer 302 at the angularposition that generated peak intensity (normal incidence).

At step 2150, the system varies the wavelength of the tunable laser andtests for the transmission characteristics of each filter.

After filter testing, at step 2152, the processing table 238 againrotates 180° presenting a new set of optical filters 196 for testing(FIGS. 12 and 14) and returning the tested optical filters 196 to theiroriginal position adjacent to linear motor 510 (FIGS. 3 and 12) forfurther processing.

At step 2154, the system drives the “X” and “Y” gantry systems (FIGS. 1and 2) to move the head 124 (FIGS. 5A and 5B) over the first testedfilter to be unloaded.

At step 2156 the system drives linear motor 510, and hence the flexureactuator assembly 294 laterally into a position adjacent a filter nest.

At step 2160, the system drives the “Z” stage downward causing vacuumprobe 152 to make contact with that filter, and applies a vacuum toorifice 164.

At step 2162, the system applies compressed air to translating stage 266thereby causing flexure actuator assembly 264 to translate and spreadjaws 262 and thereby releasing the first tested filter 196 to the vacuumprobe 152 (FIGS. 9A and 9B) of the head 124.

At step 2164, the system deposits the tested filter in the appropriateoutput tray. The system commands the “X” and “Y” stages to move thetested filter to a predetermined empty filter position over theappropriate output tray 112 (based upon the results of the test) andthen commands the “Z” stage to lower the filter on the end of probe 152until it is in position on the tray. Once in position, the systemreleases the vacuum applied to probe 152 and commands the “Z” stage totranslate upward away from that tray.

This process of unloading described in steps 2154 through 2164 isrepeated four times, once for (and at) each of the four filter nests 236containing a tested filter.

While the loading and unloading process described above indicates thatall four tested filters are unloaded from the flexures before fourto-be-tested filters are loaded into the flexures, this is notnecessary. It is equally satisfactory (and considered to be within thescope of this invention) to interleave the unloading and loading. Whenthe loading and unloading processes are interleaved, each of the fourfilter nests is sequentially unloaded and loaded in turn.

What has been illustrated and described herein is an automated apparatusfor testing optical filters. However, as the automated apparatus of thepresent invention has been illustrated and described with reference toseveral preferred embodiments, it is to be understood that the fullscope of the invention is not to be limited to these embodiments. Inparticular, and as those skilled in the relevant art can appreciate,functional alternatives will readily become apparent after reviewingthis patent specification and enclosed FIGURES. Accordingly, all suchfunctional equivalents, alternatives, and/or modifications are to beconsidered as forming a part of the present invention insofar as theyfall within the spirit and scope of the appended claims.

1. A goniometer comprising: a base; a compound member supported by thebase; a light-directing element operably mounted on the compound member,optically connected to a coherent light source, and disposed toward anoptical filter; a first actuator disposed along a first axis andoperably coupled to the base for translating the light-directing elementalong a first arcuate path disposed in a first plane; and a secondactuator disposed along a second axis and operably coupled to thecompound member for translating the light-directing element along asecond arcuate path disposed in a second plane, wherein the first planeis orthogonal to the second plane, and wherein the first and second axesare co-planar, for directing coherent light at an angle that is normalto the optical filter.
 2. The goniometer of claim 1, wherein the basecomprises: a pair of spaced-apart tip-axis base plates; and a channeledguide member disposed therebetween.
 3. The goniometer of claim 1,wherein the compound member comprises: a pair of spaced-apart tilt-axisside plates; and a tilt-axis mount disposed therebetween.
 4. Thegoniometer of claim 3, wherein the base comprises: a pair ofspaced-apart tip-axis base plates; and a channeled guide member disposedtherebetween.
 5. The goniometer of claim 4 further comprising: a firstgear set operably coupled between the first actuator and the base; and asecond gear set operably coupled between the second actuator and thecompound member.
 6. The goniometer of claim 5, wherein thelight-directing element is a collimator.
 7. The goniometer of claim 5,wherein the first and second actuators are DC motors.
 8. The goniometerof claim 5, wherein the light-directing element is a collimator, andwherein the first and second actuators are DC motors.
 9. The goniometerof claim 1 further comprising: a first gear set operably coupled betweenthe first actuator and the base; and a second gear set operably coupledbetween the second actuator and the compound member.
 10. The goniometerof claim 9, wherein the light-directing element is a collimator.
 11. Thegoniometer of claim 9, wherein the first and second actuators are DCmotors.
 12. The goniometer of claim 9, wherein the light-directingelement is a collimator, and wherein the first and second actuators areDC motors.
 13. A goniometer station comprising: a goniometer comprising:a base; a compound member supported by the base; a light-directingelement operably mounted on the compound member, optically connected toa coherent light source, and disposed toward an optical filter; a firstactuator disposed along a first axis and operably coupled to the basefor translating the light-directing element along a first arcuate pathdisposed in a first plane; and a second actuator disposed along a secondaxis and operably coupled to the compound member for translating thelight-directing element along a second arcuate path disposed in a secondplane, wherein the first plane is orthogonal to the second plane, andwherein the first and second axes are coplanar, for directing coherentlight at an angle that is normal to the optical filter; and acoherent-light splitter optically connected between the coherent-lightsource and the light-directing element.
 14. The goniometer station ofclaim 13, wherein the base comprises: a pair of spaced-apart tip-axisbase plates; and a channeled guide member disposed therebetween.
 15. Thegoniometer station of claim 13, wherein the compound member comprises: apair of spaced-apart tilt-axis side plates; and a tilt-axis mountdisposed therebetween.
 16. The goniometer station of claim 15, whereinthe base comprises: a pair of spaced-apart tip-axis base plates; and achanneled guide member disposed therebetween.
 17. The goniometer stationof claim 13 further comprising: a first gear set operably coupledbetween the first actuator and the base; and a second gear set operablycoupled between the second actuator and the compound member.
 18. Thegoniometer station of claim 17, wherein the light-directing element is acollimator.
 19. The goniometer station of claim 17, wherein the firstand second actuators are DC motors.
 20. The goniometer station of claim17, wherein the light-directing element is a collimator, and wherein thefirst and second actuators are DC motors.
 21. The goniometer station ofclaim 16 further comprising: a first gear set operably coupled betweenthe first actuator and the base; and a second gear set operably coupledbetween the second actuator and the compound member.
 22. The goniometerstation of claim 21, wherein the light-directing element is acollimator.
 23. The goniometer station of claim 21, wherein the firstand second actuators are DC motors.
 24. The goniometer station of claim21, wherein the light-directing element is a collimator, and wherein thefirst and second actuators are DC motors.
 25. A goniometer stationcomprising: a plurality of goniometers, wherein each goniometercomprises: an associated base; an associated compound member supportedby the associated base; an associated light-directing element operablymounted on the associated compound member, optically connected to acoherent light source, and disposed toward an associated optical filter;an associated first actuator disposed along a first associated axis andoperably coupled to the associated base for translating alight-directing element along a first arcuate path disposed in a firstplane; and an associated second actuator disposed along a second axisand operably coupled to the associated compound member for translatingthe light-directing element along a second arcuate path disposed in asecond plane, wherein the first plane is orthogonal to the second plane,and wherein the first and the second axes are co-planar, for directingcoherent light at an angle that is normal to the associated opticalfilter; and a coherent-light splitter optically connected between acoherent-light source and the light-directing element of each of theplurality of goniometers.
 26. The goniometer station of claim 25,wherein the base of each goniometer comprises: a pair of spaced-aparttip-axis base plates; and a channeled guide member disposedtherebetween.
 27. The goniometer station of claim 25, wherein theassociated compound member of each goniometer comprises: a pair ofspaced-apart tilt-axis side plates; and a tilt-axis mount disposedtherebetween.
 28. The goniometer station of claim 27, wherein the baseof each goniometer comprises: a pair of spaced-apart tip-axis baseplates; and a channeled guide member disposed therebetween.
 29. Thegoniometer station of claim 28 wherein each goniometer furthercomprises: a first gear set operably coupled between the first actuatorand the associated base of the first actuator; and a second gear sets,operably coupled between the second actuator and the associated compoundmember of the second actuator.
 30. The goniometer station of claim 29,wherein the light-directing elements is a collimator.
 31. The goniometerstation of claim 29, wherein the first and second actuators of eachgoniometer is a DC motor.
 32. The goniometer station of claim 29,wherein the light-directing element of each goniometer is a collimator,and wherein the first and second actuators of each goniometer are a DCmotor.
 33. The goniometer station of claim 25, wherein each goniometerfurther comprises: a first gear set operably coupled between the firstactuator and the associated base of the first actuator; and a secondgear set operably coupled between the second actuator and the associatedcompound member of the second actuator.
 34. The goniometer station ofclaim 33, wherein the light-directing element of each goniometer is acollimator.
 35. The goniometer station of claim 33, wherein the firstand second actuators of each goniometer are a DC motor.
 36. Thegoniometer station of claim 33, wherein each of the light-directingelements is a collimator, and wherein each of the first and secondactuators of each goniometer are a DC motor.
 37. A goniometer for use inan automated test station comprising: an upper stage that is configuredto be tilted about a first tilt axis; an upper stage motor coupled tothe upper stage to tilt the upper stage about the first tilt axis; alower stage upon which the upper stage is coupled that is configured tobe tilted about a second tilt axis; a lower stage motor drivinglycoupled to the lower stage to tilt the lower stage about the second tiltaxis; and a goniometer base to which the lower stage is mounted and withrespect to which the lower stage tilts; wherein the first and secondaxes intersect at a point in an optical path defined by a collimator ina plurality of upper and lower stage positions.
 38. The goniometer ofclaim 37 wherein the first and second tilt axes are disposed external tothe goniometer.
 39. The goniometer of claim 37 wherein the first andsecond tilt axes are substantially orthogonal.
 40. The goniometer ofclaim 37 wherein the first tilt axis is itself tilted when the lowerstage motor tilts the lower stage.
 41. The goniometer of claim 37wherein one of the upper and lower stages includes a spur gear drivearrangement driven by its associated motor.
 42. The goniometer of claim41 wherein the other of the upper and lower stages includes a worm geararrangement driven by its associated motor.
 43. The goniometer of claim37 wherein the optical collimator has a proximal end fixed to the upperstage and a distal free end extending away from the goniometer.
 44. Thegoniometer of claim 37, wherein the point of intersection of the firstand second axes is substantially fixed.